Endodontic systems and methods for the anatomical, sectional and progressive corono-apical preparation of root canals with dedicated stainless steel instruments and dedicated nickel/titanium instruments

ABSTRACT

A root canal is sequentially cleaned in sections from the crown to the apex by dividing it into three sections including an operative coronal portion, an operative middle portion and an apical portion. The pulp material is then sequentially removed from the portion of the root canal above the apical portion of the root canal with a set of instruments having stainless steel files. The apical portion is then cleaned with another set of instruments that have nickel/titanium files. An optional set of instruments can also be used to improve the access into the apical portion such that irrigants can be delivered to the apical portion.

BACKGROUND OF THE INVENTION

[0001] 1. The Field of the Invention

[0002] The present invention is related to the field of endodontistry.More particularly, the invention is related to systems and operatingmethods for the preparation of root canals for obturation. The systemsand methods involve the use of at least instruments which are dedicatedfor specific purposes in the inventive methods and systems and aredesigned for minimal intrusion into the apical portion.

[0003] 2. The Relevant Technology

[0004] To preserve a tooth with a pulp that is diseased or ispotentially diseased, it is generally necessary to remove as much of thepulp material as is possible from the pulp canal of the tooth, to shapethe root canal(s) without excessively weakening the root canal walls, toprevent or minimize the presence of bacteria through the use ofirrigants and dressings, and lastly, to clean the walls of the rootcanal(s) by removing the smear layer created during instrumentation ofthe root canal(s). These steps are all done to prepare the root cavityfor sealing or obturation which involves filling the root canal withbiocompatible materials, such as gutta percha, before the pulp cavity issealed, thereby promoting the healing and functional recovery of thetooth. This procedure is referred to as root canal therapy.

[0005] As indicated hereinabove, root canal preparation involves pulpremoval, cleaning of the root canal walls and shaping of the canalwalls. This is typically achieved through a guided procedure with theuse of instruments which are moved either manually, mechanically or bycombinations thereof. These instruments are files or bits that areconfigured to bore and/or cut. Mechanical instrumentation can beachieved through the use of endodontic handpieces coupled to instrumentssuch as files. The endodontic handpieces can impart rotational motion toa file, reciprocal motion by alternately rotating a file clockwise andcounterclockwise, sonic movements or ultrasonic movements.

[0006] Before endodontic therapy is begun, a preoperative x-ray image isobtained to assess the health and the pathological status of the toothand to determine the approximate initial length of the root canal(s).Once the approximate length of the root canal(s) has been determined, aninstrument can be selected for use in the root canal which has anappropriate working length.

[0007] The schematic representations shown in FIGS. 1A and 1B aresimilar to a typical x-ray image. As shown in FIGS. 1A and 1B, an x-rayimage of teeth generally show teeth 10 with sufficient clarity to viewsome of the properties of roots 12 and the root canals 14 locatedtherein, particularly the location of the radiographic apex 17. Thelocation of the radiographic apex often does not coincide with the trueapical terminus of the canal just beyond the apical foramen 16. Thedistance between radiographic apex 17 and a fixed reference position onthe occlusal surface of a tooth is used to determine the working lengthof the instruments. FIG. 1B, which is an enlarged view of root 12 ashown in FIG. 1A, shows the relative position of the radiographic apexdesignated at line 17 in relation to that of the endodontic apex and theanatomical apex designated respectively by lines 18 and 19. Thiscondition is typical of an apex in living teeth, whereas a pathologicalapex can appear in a partially autolyzed state, as shown in FIG. 34C.

[0008] Preoperative or intraoperative x-ray images of a tooth requiringendodontic treatment, such as the x-ray image depicted in FIG. 1A, areobtained by lingual placement of film packets as shown in FIG. 2 at 22which is supported by an x-ray film packet holder (not shown) and a longcone x-ray head (not shown) located outside of the cheek. Although,x-ray images obtained as shown in FIG. 2 from a buccal-lingual x-rayprojection are generally useful for determining the overallcharacteristics of a tooth, the approximate initial length of the rootcanal(s), and the working length for a file, such images provide onlylimited information regarding the overall anatomy of the root canal.

[0009] The information is limited because only one dimension of theoverall anatomy of the pulp cavity can be viewed in vivo. In thestandard buccal-lingual projection such images show only a linearprofile of the root canal and cannot show a tridimensional view of atooth and its root canal(s). Although, it would be very helpful to viewa tooth from a position between the teeth or from the interproximalspace such a mesial-distal view cannot be clearly produced when thetooth is still positioned in a patient's mouth. Since information isneeded of all three dimensions in order to correctly understand theoverall anatomy of the root canal and yet only two-dimensional images ofa tooth can be obtained, x-ray images are sometimes relied on to reachincorrect conclusions regarding the anatomy of the root canal. Moreparticularly, if not properly evaluated, x-ray images can be misleadingas to the actual length of the root canal and the position of theforamen or foramina.

[0010] The difficulties encountered by an endodontist in assessing theoverall anatomy of teeth from just the x-ray images obtained frombuccal-lingual x-ray projections can be clearly identified withreference to FIGS. 3-6. FIGS. 3A-6A are longitudinal cross-sectionalschematic views of extracted teeth taken from the front or back of therespective tooth which correspond with typical images obtained frombuccal-lingual x-ray projections. FIGS. 3B-6B are longitudinalcross-sectional schematic views of the same extracted teeth shownrespectively in FIGS. 3A-6A taken from the mesial-distal or side viewthat cannot be obtained or seen while the teeth are still positioned ina patient's mouth.

[0011] Note that by varying the angle of incidence of the x-ray beammesiodistally and distomesially additional x-ray images can be madewhich provide some additional information about the anatomy of thetooth. However, we can never obtain a three-dimensional image!

[0012] FIGS. 3-4 illustrate that in order to properly prepare a rootcanal it is necessary for practitioners to rely heavily on theirexperience, knowledge acquired through a study of typical anatomicalstructures, and on their visually acquired experience with longitudinaland transverse dental cross-sections at various heights. FIG. 3A depictsa lower premolar 30 from the buccal-lingual view of the tooth whichshows root 32 and a root canal 34 therein that appears to be rathernarrow and to have a relatively uniform perimeter along its length. FIG.3B, however, shows that when seen from the mesial-distal view, the rootcanal is initially fairly wide over more than half its length, and thentapers significantly before reaching the apical foramen 36. ComparingFIG. 3A with FIG. 3B clearly shows that when limited to knowledgederived from an x-ray corresponding to the image shown in FIG. 3A, thepractitioner may not be able to accurately assess the anatomicalstructure of the root anatomy. Additionally, FIG. 3C shows that insteadof an apical foramen there may be double, triple or quadruple foraminaas indicated in research performed by the applicant and by others. Thetriple foramina 36 a, 36 b and 36 c shown in FIG. 3C may not bedetectable when viewed only from the buccal-lingual view shown in FIG.3A.

[0013]FIG. 4B depicts an upper premolar 40 with roots 42 a and 42 b androot canals 44 a and 44 b located therein. Comparing FIG. 4A and FIG. 4Breveals a problem which is similar to the problem revealed by comparingFIG. 3A with FIG. 3B. More particularly, by comparing FIG. 3A with FIG.3B or FIG. 4A with FIG. 4B, it is easily understood that thepractitioner may not be able to accurately assess the anatomicalstructure of the root anatomy when limited to knowledge derived from anx-ray image. Since the configuration of pulp chamber 48 may be difficultto accurately and fully ascertain from only an x-ray image, apractitioners also relies, as indicated hereinabove, on accumulatedexperience, knowledge of dental anatomy, and knowledge of typicalanatomical structures.

[0014] The potential inaccuracy of a conclusion derived from informationobtained from an x-ray image is further illustrated by comparing FIG. 5Aand FIG. 5B and also FIG. 6A with FIG. 6B. More particularly, asdiscussed hereinbelow, FIGS. 5-6 show that practitioners encounteranatomies with widely varying aberrations and intercommunications ofroot canals which may not be apparent to the practitioner from thelimited information derived from x-ray images.

[0015]FIG. 5A depicts a mandibular or lower incisor 50 from thebuccal-lingual view of the tooth which shows root 52 and root canal 54.FIG. 5B depicts the same lower incisor 50 from the mesial-distal view ofthe tooth. The mesial-distal view shown in FIG. 5B clearly reveals thatroot canal 54 branches and then rejoins to have a single foramen 56.Root canal morphological variations, such as that shown in FIG. 5B, maynot be detectable by a practitioner who relies solely on a preoperativeor intraoperative x-ray image, such as the image of lower incisor 50shown in FIG. 5A.

[0016] Similarly, a root canal may branch without merging so as to yieldmultiple foramina, such as the root canal of a lower first molar 60shown in FIGS. 6A-6B. Again, the buccal-lingual view, as shown in FIG.6A, provides inadequate information when compared with the depictiontaken from the mesial-distal view of mesial root 62 b in FIG. 6B. FIG.6B reveals that branches 64 a and 64 b do not merge and accordingly havetwo foramina 66 a and 66 b.

[0017] In addition to the morphological variations in anatomy asdiscussed above, consideration should also be given to the substantiallydifferent perimetrical configurations of root canals, as revealed byvarious dental cross-sections shown in FIG. 7 and FIG. 8. Additionally,the shape of root canal perimeters varies not only between differenttypes of teeth as shown in FIG. 7 and FIG. 8 but also along the lengthof a single root canal of a tooth as is illustrated in FIGS. 9A-9B.

[0018]FIG. 7 shows a classification system devised by A. Latrou whichdivides the perimetrical anatomies of root canals into those that haveprimarily a tubular morphology and those that have primarily a laminarmorphology. Examples of root canals with tubular perimetrical anatomiesare shown at 70, 71, and 72 which are respectively primarily oval, roundand triangular. The laminar perimetrical anatomies include root canalswith essentially slit-like configurations such as those shown at 73, 74,and 75 which are respectively primarily straight, semi-lunar shaped, andfigure eight shaped due to the vestibular and lingual bulges. Thelaminar shape is more common than the tubular type root canals.

[0019]FIG. 8 shows cross-sectional views of the middle third ofdifferent teeth 80 a-80 l that have been extracted and then cut along atransverse cross-section of the tooth to show root canals 82 a-82 l aswell as corresponding pulp chambers 84 and floors or cervical aspects86. Conventional file instruments 88 are also shown inserted into rootcanals 82. From this view, which can only be seen in vitro, it isevident that a certain degree of variation occurs in the perimetricalanatomy of the pulp cavity of teeth. The practitioner may at first beunaware of such variation; however, the practitioner must keep in mindthe possibility of such variation while working with instruments in theroot canal so that all of the canal walls will be treated and theirregularities caused by greater parietal thicknesses can be removedwithout unduly weakening the walls.

[0020]FIG. 9A depicts a maxillary right upper first molar 90 with dashedcutting lines included to identify the division of the tooth intotransverse cross-sections for segmentation as shown in FIG. 9B. FIG. 9Bdisplays roots, 92 a, 92 b and 92 c of molar 90 as cut into fourrespective segments, 100-103, to clearly show the variations of rootcanals 94 a, 94 b and 94 c. Also displayed in FIG. 9B are segments 104and 105, which respectively contain the pulp chamber 98 and its floor. Acomparison of the perimeters of root canals 94 a, 94 b and 94 c startingat segment 104 as each root canal tapers to its respective apices 96 a,96 b and 96 c, clearly shows that the perimeter anatomy varies andtransitions in configuration along the entire length of each root canal.So not only must a practitioner deal with root canals having differentshapes as discussed in reference to FIG. 7 and FIG. 8, but thepractitioner must also utilize an instrument in a root canal with aperimetrical or circumferential anatomy that varies depending on theheight at which the observation is made.

[0021] From the discussion above, it is apparent that when apractitioner views a preoperative or interoperative x-ray image of atooth, the practitioner can only guess about the actual anatomy of thepulp cavity and the root canal(s) of the tooth. While the practitionermay be able to confirm that a root canal has been cleaned along thelength of the pulp chamber from the coronal portion to the apex of theroot, the length that has been contacted or abraded by the file may onlybe a portion of the root canal system.

[0022] Since it is impossible to obtain a mesial-distal view of the rootcanal or to view the perimetrical anatomy on different points along thelength of the root canal, the practitioner is prevented from obtaining aproper preliminary understanding of the overall root canal anatomy inorder to assess the necessary relationship between the canal walls andthe instrument inserted in the root canal. Accordingly, as shown in FIG.10A and FIG. 10B, when a file instrument such as instrument 114 isinserted as far as the apex into a root canal such as canal 112 a oftooth 110 a or canal 112 b of tooth 110 b and then rotated, significantportions are not cleaned.

[0023] The inability to clean all surfaces of a root canal by merelyinserting and rotating a file instrument in a root canal is furtherillustrated by FIG. 8. FIG. 8 depicts the position of file instrument 88in transverse cross-sectional views of root canals after file instrument88 has been inserted to the apex of each respective root canal. FIG. 8clearly shows that simply drilling from one position into the root canalwill often miss large sections of the perimeter of the root canal,thereby leaving portions of live, diseased or necrotic pulp materialundisturbed. If the operator is unable to apply the instrument to everysegment of the perimeter of the canal, the undisturbed pulp material mayultimately cause undue pain, lengthy healing times or even cause theprocedure to fail. Solvents or irrigants such as sodium hypochlorite maybe used to further clean the root canal.

[0024] The next step is neutralization or obturation of the root canalwhich involves coating or filling the root canal with a plasticobturation material such as heated gutta percha. The object ofobturation is to prevent the ingress of bacteria or tissue fluids whichmight act as a culture medium for any bacteria remaining within the rootcanal system by sealing the system. In order to reach the recesses withthe filling material that cannot be treated with the instruments,vertical pressure must be applied with a plugger; however, there isnever any assurance that all of the necrotic residue has been coated.There is also a risk that such techniques will cause infected materialto be pressed beyond the apex. Such an extrusion of infected materialbeyond the apex is very undesirable as it may contain polymicrobialloads or charges that may produce damaging bacteremia or cause chronicinflammations of the apical and periapical tissues.

[0025] Based on all of the foregoing observations, it can be concludedthat inadequate attention is given to understanding the dental chamberson a three-dimensional basis, the varying configurations of theperimeter of the root canal(s), the diameter of the canals, and thethickness of the walls. Note that research is still needed toinvestigate and catalog the thickness of dental walls in order toincrease understanding amongst practitioners.

[0026] The inability to fully identify the anatomy of the pulp cavityrestricts the ability of the practitioner to confidently conclude thatthe procedure has been successful. Although problems may result fromhaving incomplete information regarding the anatomy of a particular rootcanal, many practitioners using conventional methods and instruments arenot overly concerned with completely cleaning the entire root canalsince their failure rate is not at an unsatisfactory level. While theseconventional methods and instruments may result in satisfactory failurerates, it would be very beneficial to still lower the failure rate andto better preserve the integrity of teeth.

[0027] As discussed hereinbelow, most of the methods and instrumentsthat have been and continue to be employed and produced are relativelyarbitrary with regard to root canal anatomy. To compensate for thelimited understanding of the inability to contact all root surfaces andthe lack of knowledge of the actual anatomy of the root canal, manyworking methods have been devised, which in turn have prompted thecreation of a multitude of instruments of varying diameters and sizes.

[0028] With regard to operating procedures, there are two basic methodsfrom which all of the canal-preparation techniques can be derived. Thesemethods have been interpreted by various authors in an operationalcontext and also in terms of the instrumentation. The primaryconventional systems and methods for removing pulp material from theroot canal of a tooth are the apico-coronal (step-back) technique andthe corono-apical (crown-down) technique. Although these conventionalcleaning techniques both rely generally on sequential increases in thediameter of instruments inserted into the root canal, the step-backtechnique involves cleaning the root canal from the apex toward thecrown while the crown-down technique involves cleaning the root canalfrom the crown down to the apex. Each has its own unique benefits anddisadvantages which are discussed hereinbelow.

[0029] The step-back technique involves the use of various sets of fileinstruments which are sequentially inserted into a root canal after theroot canal has been exposed by removing the roof of the pulp chamber asdepicted in FIG. 11A and FIG. 11B. More particularly, before pulpmaterial 160 can be removed in accordance with the step-back technique,an instrument, such as instrument 120 shown with bur 122 in FIG. 11A andFIG. 11B, is utilized to remove the overhanging portions of enamel 152and dentin 154 in order to provide access into the pulp chamber 156.FIG. 12 depicts a set of step-back file instruments with each fileinstrument 130 comprising a handle 132 connected to a file 134 or ashaft with tines or an abrading portion. Each file has a tip 136opposite a top end 138 where file 134 joins handle 132. As viewed inFIG. 12 from left to right, the diameter at top end 138 of each fileincreases progressively from the smallest to the largest such that thediameter of 138 a is less than the diameter of 138 b. The diameter ofeach successive file at tip end 136 is also successively larger.Accordingly, the taper of each file remains essentially the same eventhough each file is progressively larger that the preceding file.

[0030] In the step-back technique, the apical portion of the tooth isprepared first and then the remainder of the canal is flared from apexto crown. This process essentially involves inserting a series ofprogressively larger files into the apex of the root canal and rotatingeach file and/or moving the file up and down in a longitudinal motionuntil a file can be inserted that is considered to be a suitablestandard size for completing the process or that meets some resistanceto rotation. The rest of the canal is then flared by sequentially usingeach file in the set, as shown in FIG. 12, with each file being largerthan the preceding file and by alternately advancing and thenwithdrawing each instrument.

[0031]FIG. 13A depicts a molar 150 being prepared by the step-backtechnique after the removal of enamel 152 and dentin 154 that extendinto pulp chamber 156, and after the first stage of the step-backtechnique has been completed. The first stage of the step-back techniqueinvolves the insertion of a file into pulp chamber 156 and into rootcanal 158 a in order to remove material 160 in the lower portion of thecanal above the apex or apical end 162 a. After the portion above apex162 a is cleaned, each file shown in FIG. 12 is sequentially inserteddownward toward apical end 162 a of root canal 158 a, starting with fileinstrument 130 a as shown in FIG. 13A. As a result of this technique,the diameter of the area being contacted at the apical portion isincreasingly larger.

[0032]FIG. 13B is a cross-sectional view taken along cutting line13B-13B in FIG. 13A of tooth 150 during cleaning of root canal 158 awith file instrument 130 a in the step-back technique. Insertion of thefiles of the other file instruments 130 b and 130 c may further cleanout material 160 because each file has an increasingly larger diameter.With each increase in diameter, the rigidity increases and theflexibility of the files decreases. As a result, it becomes increasinglydifficult for the files to adjust to or to follow the contours of theperimeter surfaces of the root canal. This reduced flexibility alsoincreases the likelihood that the files will fail to contact someportions while removing too much of the surrounding dentin 154 in someareas through excessive abrasion and resulting in overthinning of thewalls.

[0033] Note that the views depicted in FIGS. 13A and 13B depict theproblem previously discussed with regard to the difficulty in assessingthe actual root canal anatomy in vivo. When viewed in FIG. 13A, itappears that the root canal has been cleaned; however, FIG. 13B showsthat a significant portion of material 160 remains. Accordingly, whenthe root canal is viewed in an x-ray photograph which is the same viewshown in FIG. 13A, a practitioner may mistakenly believe that the toothhas been adequately cleaned. This mistaken belief may be furtherincorrectly relied on as the root canal is widened by the insertion ofthe larger files which gives an impression of complete cleaning. Thereis resultingly some possibility for failure of the root canal therapydue to incompleteness.

[0034] Not only is the completeness effected by the use of a set offiles wherein each file is more rigid than the preceding file but theability to safely move the file within the canal is also limited. Moreparticularly, the increasing rigidity results in decreased ability tonegotiate the curves in the canal. Significant problems that can resultfrom inserting increasingly rigid files and also from initiallyinserting a file all the way down to the apex includes laceration andtransportation of the apical foramen, as well as misdirection andperforation of the wall. As shown in FIG. 14A, after tooth 170 wasprepared by removal of portions of the enamel 172 and dentin 174, file132 was inserted into root canal 176 and perforated apex 178.Perforating the apex can also result from an error in estimating thelength of a root canal, by failure of a stop such as stop 140 to remainat a predetermined position or by failure to observe the calibration orgraduation hatch markings on the file, which can be used instead of astop to designate the length.

[0035] The apex can be perforated by extrusion of the infected material180 through the apex due to the force exerted by the file on thematerial as the file is pushed downward to reach the apex. As a result,the periapical region can be invaded and contaminated. The potential forextruding infected material through the apical foramen of a necrotictooth during the initial insertion of a file instrument all the way downto the apex is a particular disadvantage of the step-back technique.Another disadvantage is that the procedure has identical steps forworking in either necrotic or vital root canals. In addition to exposingthe tissue surrounding the tooth to the infected material, apicalperforations may allow irrigants, amalgam filling or obturating materialto flow out of the apex. Such apical perforations, as well as wallperforations, may delay tooth healing and may compromise the outcome ofthe therapy.

[0036] Perforations can also occur due to a failure to maintain a properworking length of the instrument during the procedure. As the canal iswidened, curvatures are straightened thereby decreasing the requiredworking length needed for the instrument to work. Accordingly, therubber stop 140 must be adjusted, thereby continually providing anopportunity for the instruments to become contaminated by bacteria. Toproperly determine the appropriate working length, many radiographs mustbe taken throughout the operation as the canal is continuously beingmodified, which alters the length. The time required to obtain the x-rayphotographs or images and to adjust the working length of theinstruments by repositioning the stops can result in a lengthy process.The step-back technique is also time intensive because a large number ofinstruments are required to complete the root canal therapy.

[0037] As shown in FIG. 14B, another problem is the formation of ledgessuch as ledge 182. Ledges can occur when a practitioner attempts toinsert a file such as file 134 as far as the apex and the file is tooinflexible to properly curve with the root canal or move around aprotrusion. When a file is too inflexible to curve or flex as needed andis halted prematurely, the downward pressure exerted on the file, inconjunction with the tendency of the file to straighten itself, causesthe tip of the file to dig into the side of the root canal and form aledge. Such ledges are difficult to bypass; and if the ledge occurs veryclose to the apex, the ledge may give the practitioner the mistakenimpression that the apex has been reached.

[0038] The crown-down technique was developed for several reasons. Itwas desired to shape the canal “conically” so as to keep the diameter ofthe foramen as straight as possible. The crown-down technique was alsodeveloped to prevent the discharge of septic material or obturationmaterial from the apex after the initial canal-preparation step and toprevent subsequent vertical condensation due to the vertical pressureused to obturate the canals with heated gutta-percha. Additionally, thecrown-down technique was intended to reduce the number of instrumentsutilized compared with the step-back technique. However, as discussedhereinbelow, significant potential problems may inherently result fromuse of the crown-down technique.

[0039] The crown-down technique generally involves the use of a set offile instruments wherein each file in the set of file instruments has aprogressively different diameter at the top of the cutting portion ofthe file, i.e., the point where the file becomes smooth and no longerhas cutting capabilities. The smooth portion may have a constantdiameter. The diameter at the top of the cutting portion of each filemay be either constant or graduated for the entire set of instrumentssuch that the top of the cutting portion of each file is progressivelylarger than that of the preceding file. As a result of thisconfiguration, the taper of each file is larger than the preceding filein the set. By using such files of increasingly larger diameters, thearea that is initially and subsequently abraded, as work proceeds towardthe apex, will always be primarily at the top portion of the root canal.

[0040] Gradual progressive conicity or taper, and the constant diameterof the tip (characteristics which, paradoxically, have been inflated,despite the prior teachings of the present applicant in earlier patents,such as Italian patents No. 1,199,941 and No. 1,169,326, and U.S. Pat.No. 4,971,556) are characteristics which are now so standard among themultitude of crown-down instruments made of nickel/titanium that havebeen introduced onto the market, that competitors have shifted towardother features of the instruments. For example, increasing value isbeing attached to the so-called “overall” originality of an operatingprocedure that uses so-called “dedicated” instrumentation to solve themultiple problems associated with root canal preparation in terms ofergonomics, operational safety, the time and cost of the procedure, andthe likelihood of success.

[0041] One example of the operational deficiency of the crown-downmethod lies in its association with instruments made of nickel/titanium.Based on the greater flexibility of files formed from nickel/titaniumcompared with files formed from steel, proponents of the crown-downmethod in conjunction with nickel/titanium files assert that such filescan better follow the curvatures of a root canal. Additionally, it hasbeen asserted that such files are more likely to stay in the center ofthe root canal, thereby decreasing the likelihood of ledging orperforating the root canal walls. As set forth hereinbelow in greaterdetail, each material has its own unique advantages and disadvantages.

[0042] The ability of a nickel/titanium file to stay in the center isnot necessarily desirable, in view of the morphology and perimetricalvariety of root canals, and particularly the variety in the uppertwo-thirds of laminar root canals. In fact when rotation is imparted toan instrument that stays in the center of the canal, the file instrumentworks simultaneously and indiscriminately on all of the walls withinreach of the file. Since root canal walls do not have equal thicknessesin all directions and at all different points along a root canal, somewalls can be overthinned or perforated, while other walls remainuntouched.

[0043] Moreover, because nickel/titanium files are more flexible thansteel files, they tend to follow the path of least resistance andtherefore cannot be used, in the same way as steel files, to be appliedactively and intentionally by the operator. As a result, even when theoperator knows the thickness of a particular portion, such as aninterference or obstruction which the operator desires to rectify orstraighten, the operator lacks the freedom to aggressively drive thefile as needed and clean the portions that are difficult to reach.Accordingly, when a nickel/titanium file is used to clean anon-cylindrically shaped root canal, the file moves only at the centerof the canal and/or the area of least resistance and fails to remove allof the necrotic tissue.

[0044]FIGS. 15A, 15B, 15C, 15D and 15E depict transverse cross-sectionsof tooth 190 that has been cleaned in a manner that has resulted ineither overthinning of root canal walls, perforation of a root canalwall, excessively weakening of the walls of the tooth or a failure tofully contact all of the canal walls. These problems can be easilycaused by the passive, self-guiding use of nickel/titanium files withprogressively larger tapers in the transition from the first instrumentto the next one in the set. These problems can also be caused by theincreasing rigidity, in accordance with the crown-down technique, whichprevents the files from being laterally moved to enable the files toclean the entire perimeter of the root canal. The cross-sections shownin FIGS. 15A-E may be considered independently from each other as beingcross-sections from different teeth or from a single tooth such thatFIG. 15A shows two roots 192 a and 192 b of a tooth 190 while FIGS.15B-15E show root canal 194 a as the root canal tapers to the apex.

[0045]FIG. 15A depicts the overthinning that can occur to the furcationwalls of root canals 194 a and 194 b near the bifurcation as a resultfrom the indiscriminate thinning of the distal walls of the root canalsby maintaining a file instrument in a central location during workingrotation. The resulting boreholes are shown at 196 a and 196 b while theoutlines of root canals 194 a and 194 b before cleaning are shown inphantom lines. Such overthinning and potential furcal perforation canhave devastating results. The inability to adequately direct a file usedin accordance with the crown-down technique based on the practitioner'sknowledge of the relative thicknesses of the portions of canal walls isa significant disadvantage of the technique.

[0046]FIG. 15B shows a lateral perforation that has occurred when a holewas made through dentin 198 and cementum 197 during the cleaning of rootcanal 194 a. The lateral perforation resulting from the formation ofborehole 196 a may be obscured from the x-ray due to concavities orcurvatures in the root canal. The practitioner may then mistakenlyconclude that the root canal has been successfully cleaned withoutrealizing that there is a perforation.

[0047] In FIG. 15C, the segment shown of root canal 194 a was overlythinned during the cleaning of root canal 194 a as borehole 196 a isshown extending through dentin 198 and into the cementum 197. Asmentioned in reference to FIG. 15B, the formation of borehole 196 a maybe obscured from the x-ray view. As a result, the practitioner may notrealize that the borehole extends into the cementum and may thereforemistakenly conclude that the root canal treatment has been successful.Infective bacteria that remained in the root canal, perhaps in theportions that were not contacted with the files, as well as toxinsproduced by the bacteria may then permeate through the cementum andcause infection or other complications.

[0048]FIG. 15D provides an example of a cross-section of a laminar-typeroot canal cleaned by the crown-down technique which may result insuccessful root canal therapy since the instrumentation has not resultedin a perforation and the cementum 197 has not been exposed. Although,problems such as perforations or overthinning have been avoided, FIG.15D shows that large portions of root canal 194 a remain untoucheddespite the change in morphology through the formation of large borehole196 a. Note that the change in the morphology of the canal shown in FIG.15D resulting from crown-down technique instrumentation occurs due todrilling in a passive, circular manner with instruments having gradualand progressive tapers. The failure to contact significant portions of aroot canal while forming a large borehole in a root canal as shown inFIGS. 15B-D is a very typical result of the crown-down technique sincemost root canals can be characterized as a laminar-type root canal.

[0049] It would be preferable to avoid the risk posed by failing tocontact significant portions of the root canal as shown in FIG. 15D.Since the practitioner is prevented from removing and cleaningessentially all pulp material, the practitioner cannot be assured of thereliability of the treatment. Additionally, the practitioner may notsuspect that the working instruments have failed to contact everysegment of the root canal as use of a set of files with increasinglygreater tapers can contribute to a potentially incorrect conclusion thatcleaning by such a conventional process has resulted in removing allmaterial from root canal 194 a. Further, the x-ray view of tooth 190, aswith the step-back technique shown in progress in FIGS. 13A and 13B,would give the impression that the root canal had been cleaned. Itshould also be remembered that while rotation of a set of passivelyactuated files, with increasingly greater tapers, in the center of thecanal, in accordance with the crown-down technique, may yield aconfiguration as shown in FIG. 15D and result in successful root canaltherapy, there is a significant hazard, as shown in relation to theFIGS. 15A-C, due to the passivity of the instruments when linked tocanal diameters and wall thicknesses that are still statisticallyunknown.

[0050] As in the configuration shown in FIG. 15D, the configurationshown in FIG. 15E may also result in successful root canal therapy—butonly for canals of the wholly tubular type. Although, borehole 196 adoes not extend through dentin 198 and into the cementum 197, thediameter of the preparation or borehole 196 a is neverthelesssignificantly larger than that of the original root canal was as shownby the phantom lines at 194 a. The excessive thinning of the dental wallmay resultingly significantly weaken the resistance of the walls to thestress of chewing, and may also cause a fracture of the root.

[0051] From the above discussion in relation to FIGS. 15A-E, it is clearthat the actual morphology of the canals is not sufficiently consideredwhen using this method and that the use of files with increasinglylarger tapers limits the range of motion of the files. Morespecifically, due to the use of files with successively larger taperswhich therefore are increasingly rigid, each file, if actuatedpassively, is primarily limited to being rotated without substantiallateral movements guided by the operator. Since the majority of filesare of the laminar type, this limitation poses a significant problem.Without the ability to laterally move the files, it is not possible tomake contact with every segment of the perimeter of the canal and someportions may receive too much contact.

[0052] In any event, if the files are rotated passively in a laminarcanal or a canal which has a laminar-type anatomy for the firsttwo-thirds of the canal, the result is a circular opening whose diametercorresponds to that of the file that was used. The file typically staysin the center of the canal during rotation, such that the tip of eachfile acts like a fulcrum and “ideally” stays in the same position as arotation point. Since each successive file can move less laterally, eachfile simply makes a bigger borehole than the preceding file.Accordingly, the files cannot clean a root canal without significantlyaltering the original anatomy by leaving a footprint or boreholecorresponding to the configuration of the instruments used. Morespecifically, the result is a footprint or borehole with a perimeterthat corresponds to the perimeter of the biggest file that extends wellbeyond the original anatomy of the root canal and yet in most instancesdoes not adequately clean significant portions of the root canal.

[0053] As discussed above, the flexibility of the files used in thecrown-down technique, which are typically formed from nickel/titanium,prevents the files from being successfully urged against the perimeteror against the various surface features of the root canal. As alsodiscussed above, the flexibility of the files also increases thetendency of the files to remain in the center or at the location whereless resistance to movement is encountered. Accordingly, the flexibiityof the files also contributes to the configuration of borehole 196 a,which substantially deviates from the original anatomy of the root canal194 a.

[0054] There are also other disadvantages to the use of nickel/titaniumfiles. The flexibility of nickel/titanium files increases the likelihoodthat the file may bend and be deformed upon encountering a hardsubstance. Since nickel/titanium files are more fragile and moreflexible than stainless steel files, the nickel/titanium files can breakmore easily and unexpectedly than steel files. When a nickel/titaniumfile instrument is used with a large file diameter the flexibilitydecreases to the point of being as rigid as stainless steel and yetbreaks more easily. More particularly, beyond a certain diameter, theupper halves of larger diameter files are still as rigid as that ofsteel files while the flexible lower halves of nickel/titanium fileinstruments are more prone to break.

[0055] Additionally, rotation of a file in a canal that has a laminarupper two-thirds exposes the tip of the file to the risk of breakingwhen the tip of the file is embedded or stuck in a canal whose diameteris smaller than its own diameter! To avoid breaking the tip when it isembedded or stuck in a canal whose diameter is smaller than the diameterof the tip, operators who use nickel/titanium files are advised toemploy catheterization in order to obtain a prophylactic widening of thecanal, using a series of instruments with increasingly larger tipdiameters.

[0056] Another disadvantage of nickel/titanium files is that nickelembodied in the alloy may potentially result in an allergic reaction.Further, nickel/titanium files costs about four times as much as steelfiles and yet nickel/titanium files generally wear out faster than steelfiles. Nickel/titanium files wear out so quickly that some manufacturersmark their products as being intended for single use only.

[0057] Moreover, the crown-down instruments currently available on themarket, almost all of which are made of nickel/titanium, in somerespects violently conflict with the use of the crown-down method,because, paradoxically, these instruments are smooth in areas where themethod requires that they first perform a cutting action. The reason forthis deficiency lies in the length of the abrading portion of theinstruments, which portion is only 16 mm long and which extends into asmooth portion leading to the handle, onto which rubber stops areaffixed, or into which millimeter-based calibration marks are engravedin order to allow visual control of the working depth of the instrumentin the canal. For example, note in FIGS. 13A and 13B that when file 134a is inserted into root canal 162 a that the abrading portion 138 a isnot long enough to contact the dentinal shelves 166, instead the upperportion of the file is smooth shank portion 136 a. Since the length ofthe root canal often exceeds the standard 16 mm length abrading portionof conventional instruments, see Table 1 hereinbelow, we may reasonablyask how an instrument which, according to the crown-down method, issupposed to prepare a canal starting at its coronal third, can performthis task if its coronal segment is smooth! TABLE 1 Average Root CanalLengths Tooth Upper Lower Central 23 mm 20.5 mm Lateral 22 mm 21 mmCanine 26.5 mm 25.5 mm First Premolar 20.5 mm 20.5 mm Second Premolar21.5 mm 22 mm First Molar 20.5 mm 21 mm Second Molar 20 mm 20 mm

[0058] Obviously, from a review of the average root canal lengths inTable 1, significant segments of a root canal cannot be abraded bystandard 16 mm long abrading portions of conventional files and arecontacted only by the smooth portion of the files.

[0059] Although, the crown-down technique typically enables apractitioner to more efficiently clean a root canal than the step-backtechnique, they both require the practitioner to utilize many differentinstruments. The need to frequently change the cleaning instrumentresults in significant time requirements for cleaning a root canal.However, careful instrumentation in accordance with either tedious timeconsuming method does not avoid the problems set forth above in relationto apical perforation, wall perforation, overthinning or failure toclean all of the wall surfaces.

[0060] Based on the foregoing observations, methods and systems areneeded in the endodontic arts which enable a dental practitioner toremove and clean essentially all pulp material in a root canal requiringroot canal therapy.

[0061] It would also be an advancement in the endodontic arts to providemethods and systems that are based on the three-dimensional reality ofteeth and do not relate solely to buccolingual x-ray views, therebyenabling a practitioner to remove and clean pulp material in a rootcanal without compromising the strength of the walls and the apicalanatomy.

[0062] It would also be a beneficial development in the endodontic artsto provide methods and systems which encourage perimetrical contact ofthe instruments with the canal walls.

[0063] Additionally, it would be an advancement in the endodontic artsto provide methods and systems that enable a practitioner to remove andclean pulp material in a root canal in a manner that is less likely toresult in failure due to bacterial contamination, overly thinning theroot canal, perforations or due to infected material being pushed beyondthe root from the coronal aspects of canals.

[0064] Finally, it would also constitute progress in the endodontic artsto provide methods and systems which yield a predictable success rate,minimal risk of breaking an instrument, lower costs, and an abbreviatedoperating time or an operating time that is at least as efficient asconventional techniques.

SUMMARY AND OBJECTS OF THE INVENTION

[0065] An object of the present invention is to provide, methods andsystems which enable a dental practitioner to remove and cleanessentially all pulp material in a root canal requiring root canaltherapy by progressively cleaning sections of the root canal from thecrown to the apex.

[0066] Another object of the present invention is to provide methods andsystems developed based on the three-dimensional reality of teeth andnot just buccolingual x-ray views, thereby enabling a practitioner toremove and clean pulp material in a root canal without compromising thestrength of the walls and the apical anatomy.

[0067] An additional object of the present invention is to providemethods and systems which encourage perimetrical contact of theinstruments with the canal walls.

[0068] Additionally, another object of the present invention is toprovide methods and systems that enable a practitioner to remove andclean pulp material in a root canal in a manner that is less likely toresult in failure due to bacterial contamination, overly thinning theroot canal, perforations or due to infected material being pushed beyondthe root from the coronal aspects of canals.

[0069] Finally, it is an object of the present invention to providemethods and systems which yield a predictable success rate, minimal riskof breaking an instrument, lower costs, and an abbreviated operatingtime or an operating time that is at least as efficient as conventionaltechniques.

[0070] Some of the features of the invention which enable these objectsto be achieved are summarized hereinbelow.

Root Canal Terminology

[0071] Rather than speaking generally of “canals” in connection withoperative practice, the present applicant prefers the term “canalelement”, in order to emphasize that each canal has its own “anatomicalpersonality” with which the operator should be familiar. For example,one canal element may have a perimeter shape which is primarily laminaraccording to the Latrou classification system discussed in the abovesection entitled the “Background of the Invention” while another canalelement may be tubular. Even in a single tooth which has multiple canalelements, it is important to bear in mind that each canal element has aunique morphology. When referring to a polyradiculated tooth, which hasmore than one canal element, such as an upper first premolar, applicantprefers the term “canal apparatus” when referring to a set of canalelements.

[0072] Applicant utilizes a terminology based on the methodologydisclosed herein. The term “operative canal” refers to the pathway whichstarts at the occlusal surface of the tooth, continues with the cameralwall segment and the anatomical canal per se, and finally reaches theforamen. Of course, the anatomical root canal extends from the pulpchamber or the floor of the pulp chamber to the apex.

[0073] The operative root canal is divided into three sections orportions which are referred to herein as “the operative coronalportion”, “the operative middle portion” and “the apical portion”. Theoperative coronal portion essentially includes the access cavity walls.The operative middle portion is the upper portion of the anatomical rootcanal while the apical portion is the lower portion of the anatomicalroot canal. A typical apical portion is the last or bottom 3 mm of theanatomical root canal.

[0074] The terms “operative coronal portion”, “operative middle portion”and “apical portion” are unique terms that are distinct from theterminology conventionally utilized to refer to segments of a rootcanal. In the conventional crown-down method, the canal is customarilydivided into the so-called “three thirds”, including: the crown, themiddle third, and the apical third. In reference to the conventionalcrown-down method, it is common to use the term “coronal third” to referto the first part of the “anatomical” canal, originating at the floor ofthe pulp chamber or the upper limit of the middle third into which atooth is customarily divided, with a theoretical line at the height ofthe neck.

Methodology Overview

[0075] During the root canal therapy, the pulp chamber can be opened toexpose the anatomical root canal by any conventional method orinstrument. Additionally, conventional methods and instruments can beused to prepare the operative coronal portion. However, unique methodsand instruments are used in the operative middle portion whilepreferably simultaneously abrading the operative coronal portion.Additionally, after the operative middle portion has been cleaned,unique methods and instruments are used to improve access into theapical portion and to then clean the apical portion.

[0076] The present applicant developed the methodology disclosed hereinbased on the anatomical reality discussed above in the section entitled“Background of the Invention”. By envisioning the canal in which theyare operating as starting at the occlusal surface, practitioners canimmediately identify any “interferences” or obstructions, as well as anyprotrusions of enamel, which may be disregarded. As a result, theinstruments disclosed herein come into contact with every segment of thecanal walls, including the obstructions, in order to achieve anatomicalwidening and also the rectification or straightening of the first twoportions of the canal which include the operative coronal portion andthe operative middle portion. This procedure opens the pathway for thepreparation of the apical portion of the canal.

[0077] The methodology disclosed herein involves the use of distinctinstruments in the three portions of the anatomical root canal indifferent phases such that the root canal is cleaned progressively andsectionally. The instrument(s) associated with each phase have beendesigned specifically for that particular phase and accordingly haveunique customized characteristics and features. The instruments aredescribed hereinbelow after explaining the procedures for completingeach phase.

[0078] By cleaning the root canal in sections, the instruments can beadapted to the perimetrical or perimetral anatomy of the root canal. Asa result, the entire perimeter or substantially all of the perimeter iscontacted and cleaned along the length of the perimeter withoutsubstantially altering the configuration of the perimetrical anatomy.For example, a perimetrical anatomy that was primarily tubular orlaminar perimetrical anatomy will be enlarged but will still beprimarily tubular or laminar. There will not be a large round boreholein the canal superimposed on the original perimetrical anatomy whichcorresponds to the diameter of the file that is used; as is the casewith the nickel/titanium files that stay in the center of the canal evenwhen the canal is laminar.

[0079] Additionally, the invention also enables the practitioner toprepare root canals in accordance with the anatomy of the root canal,even though the practitioner may not have been able to adequatelyidentify the overall anatomy due to the inability to see the root canalas is the case from the mesial-distal view using standard radiography.Further, the invention also enables the practitioner to adapt to thecontours of the root canal of all different types of teeth, by guidinginstruments that have been designed to come into contact with everyperimetrical segment of the walls.

Interferences and Rectification

[0080] The term “interference” refers to everything in the operativecanal that hinders the rectilinear insertion of the instruments used,during the final cleaning phase of the procedure, preparation of theapical portion. The term “rectification” refers to the placement of theoperative coronal portion or access cavity on the same axis as theoperative middle portion. Rectification is achieved through the removalof interferences from the operative coronal portion and preferably fromthe operative middle portion of the operative canal as well.

Instrumentation of the Operative Coronal Portion

[0081] In this phase, the access cavity is created, after elimination ofall of the coronal tissue from a carious and weak tooth, and afterremoval of any infiltrated restoration(s). The access cavity is alsocreated prior to coronal reconstruction, if considered necessary inorder to facilitate the installation of the dam.

[0082] It is not necessary to perform a prophylactic cuspidal flatteningor cuspidectomy in accordance with the methodology as disclosed herein.However, it may desirable to perform a cuspidectomy with some teeth,particularly lateral postcanine quadrants, in order to create a flatreference plane for the stop, to create an approach nearer to the pulparhorns, to eliminate occlusal contact, and to reduce the masticatorystress on a weakened coronal structure. Weakening of the coronalstructure is typically caused by the primary carious process and by thesubsequent removal of the roof or top of the chamber due to the need tocreate the cavity that allows access to the pulp chamber and to the rootcanal. However, in view of the fact that the top of the chamber is thenatural connection between the cuspids, and that after destruction ofthe top of the chamber, which connects the cuspids, the diameter of thebase of the cuspidal columns remains weak in terms of resisting lateralmasticatory stress; the operator needs to be assured of the usefulnessof performing the prophylactic cuspidectomy on the postcanine teeth.

[0083] Apart from avoiding the risk of fractures, the rehabilitativereconstruction of the root canal element may subsequently befacilitated.

Instrumentation of the Operative Middle Portion

[0084] The most important part of this phase is the determination of theso-called “working length” of the first two portions of the operativeroot canal including the operative middle portion and the operativecoronal portion. The methods for identifying the working length involvethe use of x-rays or videography, performed with the aid of a centeringdevice and through use of the long-cone method. After the working lengthhas been determined, then the proper instruments can be selected for usein the preparation of the operative middle portion.

[0085] The working length is determined by measuring the canal axis fromthe occlusal plane, in order to arrive at the apical limit of the rootas indicated on the x-ray. A distance of 3 mm is deducted from themeasured length. The result is the maximum working depth that theoperative middle portion instrument(s) should reach. The foregoingcalculations also figure in the predetermination of the working lengthsfor all other instruments utilized in the procedure. The instrumentspreferably are selected to have files with lengths that are equal to theworking length; however, stops may also be used to ensure that the fileshave the desired working length.

[0086] The preparation of the first two portions also involvescatheterization. Additionally, this phase involves the anatomicalwidening of the perimeter of the operative middle portion as well as theremoval of the interferences from the operative coronal portion and theoperative middle portions, thereby allowing the rectification of thefirst two portions of the operative root canal. One of the instrumentused during this phase may have a file with an upper portion that iscovered with abrasive material or grit such as diamond particles inorder to aggresively abrade the upper region of the operative middleportion and the operative coronal portion.

[0087] Please note that during preparation of the operative middleportion and rectification of the first two portions, any and allintrusion of the instrument(s) into the apical portion is avoided. Theboundary between the operative middle portion and the apical portion hasbeen estimated to be located between 3 mm and 5 mm from the end of theroot canal, as shown on the x-ray. After preparation of the operativemiddle portion and rectification of the first two portions have beencompleted, the procedure moves to the third stage, in which the apicalportion is prepared.

[0088] After the working length has been determined for the first twoportion including the operative coronal portion and the operative middleportion, the operator selects an instrument from a set of instrumentsdesigned for use in the operative middle portion. The instruments arepreferably held in a mini-container whose length is about the same asthe identified working length of the instruments.

[0089] The contours of the perimeter of the root canal in the operativemiddle portion are followed as the file of the instrument(s) is flexedor curved against the surfaces of the root canal and simultaneouslymoved in a cleaning motion. Since the contours are followed, theperimeter is widened and smoothed but the original shape is notsubstantially altered.

Preparation of the Apical Portion

[0090] After the operative middle portion has been cleaned, the apicalportion may be cleaned by several different techniques or combinationsthereof One method involves no abrasive instrumentation within theapical portion just appropriate just insertion of appropriate irrigationinstruments. Since removal of the pulp material from the operativemiddle portion removes the majority of bacteria in the pulp canal, ithas been found that it is not necessary to abrade the apical portion.

[0091] Irrigants are delivered into the apical portion to maintain thedebris derived from cleaning the root canal in suspension. The debris isthen removed as the particles of the smear layer yielded from the actionof the files used to prepare the canal may result in clogging the apicalportion of the root canal with a plug. After the debris has beenremoved, the proper preparation and filling of the apical portion of theroot canal can be achieved.

[0092] By eliminating or minimizing abrasive instrumentation within theapical portion, the potential for complications is diminished. Asdiscussed above in the Background, most errors in performing root canalsoccur during instrumentation of the root canal. The apical portion isthe most delicate part of the root canal and it is the most distallylocated. Accordingly, it is highly advantageous to just irrigate andthen remove the irrigant and debris, since many complications occurduring abrasive instrumentation.

[0093] However, in some instances, it may be necessary to improve accessinto the apical portion such that an irrigation needle can be deployedto deliver irrigants to the apical portion. Access into the apicalportion is improved by widening, for example, at least the entrance ofthe apical portion or the entire apical portion.

[0094] Alternatively, another method involves the use of a set ofinstruments designed for cleaning the apical portion in an abrasivemanner. Such a method may be initiated directly after the operativemiddle portion of the operative root canal has been cleaned. However, itmay be necessary to have two phases of instrumentation within the apicalportion of the operative root canal including widening and abrasivecleaning of the apical portion. More particularly, it may be necessaryto improve the access into the apical portion before performing theabrasive instrumentation by widening the transition between theoperative middle portion and the apical portion to enable irrigants tobe delivered into the apical portion.

[0095] Before preparation of the apical third is begun by one of theabove described methods, the apical and periapical condition of theelement is evaluated, in accordance with the following guidelines. Forliving or necrotic teeth “without rearrangement of the apex” or apicalrarefaction, the instrument(s) should be kept no closer than 2 mm fromthe apex as shown on the x-ray image. Conversely, for necrotic teethwith apical autolysis, the preparation work may be performed up to adistance of 1 mm from the apex as shown on the x-ray image. Thepredetermination of the widening of the canal leading to the apex, andthe widening of each root canal for polyradiculated teeth, should bemade bearing in mind the guidelines for the widening limits set forth inthe morphometric data provided in Tables 2 and 3.

[0096] In most cases, the radicular apex contains the final segment ofthe main canal, which divides into a delta configuration as discussedabove in reference to FIG. 3C. This structure is hard to detect withx-rays. Therefore, the morphology of the dental apex is unpredictable,and the location of the junction between the cementum and dentin in anyendodontic apex is random Likewise random is the hypothetical apicalconstriction that can be detected by the most expert professionals. Adegree of confidence can be obtained through the use of electronicmeasurement devices in living canals that have not been treated withliquid medications, but only when the foramen has been passed, in orderto be subsequently withdrawn into the canal with a probe instrument.This maneuver should be avoided in necrotic canals, because of the riskof carrying germs beyond the apex.

[0097] The guidelines discussed above should be kept in mind whenredetermining the approximately working length to the apex after theoperative middle portion has been prepared. It is necessary toredetermine the working length as the working length has likely changeddue to the instrumentation of the operative middle portion.

Instruments

[0098] The operative middle portion of the operative root canal iscleaned with a first instrument or set of instruments. The root canal,including the apical portion, is then cleaned with an irrigationinstrument.

[0099] An optional instrument or set of instruments can then be used toimprove the access into the apical portion to enable irrigants to bedelivered into the apical portion from an irrigation needle. An optionalinstrument or set of instruments is provided to abrasively clean theapical portion of the operative root canal after the operative middleportion of the root canal has been cleaned and after the access into theapical portion has been widened.

[0100] Each instrument in the first set of instruments comprises ahandle connected to a file with an abrasive surface or in other words ashaft with tines or an abrading portion. Each file has a length suchthat the operative middle portion of the operative root canal is cleanedwithout significantly removing pulp material from the apical rootportion. Additionally, each file is designed to have a taper that islarger than the taper of each preceding file. Each file or shaft has anabrading portion for abrading the surfaces or walls of the root canal.In contrast to conventional files, as set forth in greater detailhereinbelow, the abrading portion may extend along the entire length ofthe file to enable the instrument to be used to clean the operativemiddle portion while also abrading the operative coronal portion.

[0101] The files of the instruments in the first set are preferablyformed from stainless steel to enable the file to be moved in thedesired manner. The files of the instruments in the first set aredesigned such that each file has sufficient flexibility to be flexed orcurved to urge the abrading portion against the surfaces of the rootcanal and sufficient rigidity to apply pressure against the surfaces ofthe root canal as the abrading portion of the file is urged against thesurfaces of the root canal and simultaneously moved in a cleaningmotion. Additionally, the files have adequate resilience to avoid beingsubstantially deformed as the file is flexed or curved to urge the file,particularly the abrading portion, against the surfaces of the rootcanal.

[0102] Each instrument in the optional set of instruments used toimprove or widen the access for the introduction of an irrigation needleto the apical portion comprises a handle connected to a file. Each fileterminates at a tip and each file is configured with an abradingportion. Each file has a length sufficient to at least approximatelyreach the apex and to enable the abrading portion of the files toimprove the access into the apical portion of the root canal.

[0103] Each instrument in the optional set of instruments used to cleanthe apical portion comprises a handle connected to a file. These filesare preferably formed from nickel/titanium. Each file terminates at atip and each file is configured with an abrading portion. Each file hasa length sufficient to at least approximately reach the establishedapical working limit and to enable the abrading portion of the files tosubstantially contact and clean the pulp material in the apical portionof the root canal. The tip of the file is preferably rounded to preventledging.

[0104] These and other objects and features of the present inventionwill become more fully apparent from the following description andappended claims, or may be learned by the practice of the invention asset forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0105] In order that the manner in which the above-recited and otheradvantages and objects of the invention are obtained, a more particulardescription of the invention briefly described above will be rendered byreference to a specific embodiment thereof which is illustrated in theappended drawings. Understanding that these drawings depict only atypical embodiment of the invention and are not therefore to beconsidered to be limiting of its scope, the invention will be describedand explained with additional specificity and detail through the use ofthe accompanying drawings listed hereinbelow.

[0106]FIG. 1A is a perspective view of an x-ray image of severaladjacent teeth taken in vivo.

[0107]FIG. 1B is an enlarged perspective view of a root of a tooth shownin FIG. 1A.

[0108]FIG. 2 is a perspective view of an x-ray film positioned adjacentto teeth to produce an image as shown in FIG. 1A.

[0109]FIG. 3A is a longitudinal cross-sectional view of an extractedlower premolar to show the anatomy of the tooth from the buccal-lingualview.

[0110]FIG. 3B is a longitudinal cross-sectional view of the extractedlower premolar shown in FIG. 3A from the mesial-distal view.

[0111]FIG. 3C is an enlarged longitudinal cross-sectional view of anapex which divides into a delta configuration having three apicalforamina. This configuration is presented as a possible alternative tothe configuration of the tooth shown in FIG. 3B.

[0112]FIG. 4A is a longitudinal cross-sectional view of an extractedupper premolar to show the anatomy of the tooth from the buccal-lingualview.

[0113]FIG. 4B is a longitudinal cross-sectional view of the extractedupper premolar shown in FIG. 4A from the mesial-distal view.

[0114]FIG. 5A is a longitudinal cross-sectional view of an extractedlower incisor to show the anatomy of the tooth from the buccal-lingualview.

[0115]FIG. 5B is a longitudinal cross-sectional view of the extractedlower incisor shown in FIG. 5A from the mesial-distal view.

[0116]FIG. 6A is a longitudinal cross-sectional view of an extractedlower first molar to show the anatomy of the tooth from thebuccal-lingual view.

[0117]FIG. 6B is a longitudinal cross-sectional view of the extractedlower first molar shown in FIG. 6A from the mesial-distal view.

[0118]FIG. 7 is a cross-sectional view of extracted teeth which havebeen cut along into transverse cross-sectional segments to show thegeneral categorization of root canal perimetrical anatomies.

[0119]FIG. 8 is a cross-sectional view of extracted teeth which havebeen cut along into transverse cross-sectional segments to show theanatomy of various root canals.

[0120]FIG. 9A is a schematic perspective view of an extracted maxillaryright first molar with cutting lines which show the division of thetooth into transverse cross-sectional segments.

[0121]FIG. 9B depicts the cross-sectional segments of the molar shown inFIG. 9A to clearly show the variations of the root canals.

[0122]FIG. 10A is a perspective view of a prior art instrument cleaninga tooth that has been partially cut-away to reveal the inability of theinstrument to clean the root canal.

[0123]FIG. 10B is a perspective view of a prior art instrument cleaninganother tooth that has been partially cut-away to reveal the inabilityof the instrument to clean the root canal.

[0124]FIG. 11A is a longitudinal cross-sectional view of a burr beingutilized to remove the overhanging enamel and dentin above the pulpchamber.

[0125]FIG. 11B is a longitudinal view of a burr extending through theenamel and the dentin into the pulp chamber.

[0126]FIG. 12 is a perspective view of a prior art set of endodonticinstruments utilized in the step-back technique.

[0127]FIG. 13A is a longitudinal cross-sectional view of a tooth beingcleaned with a file instrument used in the step-back technique.

[0128]FIG. 13B is a longitudinal cross-sectional view of the tooth shownin FIG. 4A taken along cutting line 13B-13B, which shows the portion ofthe root canal which cannot be viewed in vivo.

[0129]FIG. 14A is a longitudinal cross-sectional view of a toothdepicting apical perforation during cleaning of the root canal.

[0130]FIG. 14B is a longitudinal cross-sectional view of a toothdepicting ledging during cleaning of the root canal.

[0131]FIG. 15A is a transverse cross-sectional view of a tooth depictinga root canal cleaned by a prior art technique that has resulted in overthinning of the root canal.

[0132]FIG. 15B is a transverse cross-sectional view of a tooth depictinga root canal cleaned by a prior art technique that has resulted inlateral perforation.

[0133]FIG. 15C is a transverse cross-sectional view of a tooth depictinga root canal cleaned by a prior art technique that has resulted in overthinning of the root canal.

[0134]FIG. 15D is a transverse cross-sectional view of a tooth depictinga root canal cleaned by a prior art technique that has resulted in overthinning of the root canal.

[0135]FIG. 15E is a transverse cross-sectional view of a tooth depictinga root canal cleaned by a prior art technique that has resulted in overthinning of the root canal.

[0136]FIG. 16A is a perspective view of a set of endodontic instrumentsfor cleaning of the coronal portion and operative middle portion of aroot canal.

[0137]FIG. 16B is an enlarged perspective view of a tip of one of thefiles of an endodontic file instrument shown in FIG. 16A.

[0138]FIG. 17A is a perspective view of another embodiment of a set ofendodontic instruments for cleaning of the coronal portion and operativemiddle portion of a root canal.

[0139]FIG. 17B is an enlarged perspective view of a tip of one of thefiles of an endodontic file instrument shown in FIG. 17A.

[0140]FIG. 18A is a perspective view of another embodiment of a set ofendodontic instruments for cleaning of the coronal portion and operativemiddle portion of a root canal.

[0141]FIG. 18B is a perspective view of another embodiment of a set ofendodontic instruments for cleaning of the coronal portion and operativemiddle portion of a root canal.

[0142]FIG. 18C is another embodiment of a file tip of an endodontic fileinstrument shown in FIG. 18B.

[0143]FIG. 19A is a longitudinal view of a tooth with an exposed pulpchamber.

[0144]FIG. 19B is a longitudinal cross-sectional view of of the toothshown in FIG. 19A with a file portion of a file instrument 200 ainserted into the root canal up to the apical portion.

[0145]FIG. 19C is a longitudinal cross-sectional view of the tooth shownin FIG. 19B taken along cutting line 19C-19C to depict the cleaning ofthe pulp material from the operative middle portion of the root canal.

[0146]FIG. 19D is a longitudinal cross-sectional view of a tooth with afile portion of a file instrument 220 a inserted into the root canal upto the apical portion and being moved by a handpiece.

[0147]FIG. 19E is a longitudinal cross-sectional view of the tooth shownin FIG. 19D taken along cutting line 19E-19E to depict the fileinstrument 220 d being moved by a handpiece to clean the pulp materialfrom the operative middle portion of the root canal.

[0148]FIG. 19F is a longitudinal cross-sectional view of the tooth shownin FIGS. 19A-C depicting a coronal portion and an operative middleportion of a root canal which have been cleaned by the removal of thepulp material.

[0149]FIG. 19G is a longitudinal cross-sectional view of the tooth shownin FIG. 19F to show that essentially all pulp material has been removedfrom the coronal portion and the operative middle portion of the rootcanal.

[0150]FIG. 20A is a depiction of a practitioner employing an endodonticirrigation tip to demonstrate the convenience of employing the angledtip.

[0151]FIG. 20B is a view of a cross section of a tooth with the apicalroot portion being irrigated by the endodontic irrigation tip shown inFIG. 20B.

[0152]FIG. 21 is a perspective view of an optional set of endodonticinstruments for improving the access into the apical portion of a rootcanal.

[0153]FIG. 22 is a perspective view of an optional set of endodonticinstruments for cleaning the apical portion of a root canal.

[0154]FIG. 23 is a perspective view of another embodiment of an optionalset of endodontic instruments for cleaning the apical portion of a rootcanal.

[0155]FIG. 24 is a perspective view of an additional embodiment of anoptional set of endodontic instruments for cleaning the apical portionof a root canal.

[0156]FIG. 25 is a longitudinal cross-sectional view of a tooth with afile inserted into a root canal having a length that is sufficient toreach the apex.

[0157]FIG. 26A is a longitudinal cross-sectional view of a tooth with aroot canal that has been cleaned.

[0158]FIG. 26B is a longitudinal cross-sectional view of the tooth shownin FIG. 26A taken along cutting line 26B-26B to show that essentiallyall pulp material has been removed from the root canal.

[0159]FIG. 26C is an enlarged transverse cross-sectional view of thetooth shown in FIG. 26A taken along cutting line 26C-26C to show thatthe anatomy of the root canal has not been substantially altered by thecleaning thereof and to show the shaping of the canal in preparation offilling the root canal.

[0160] FIGS. 27A-J are transverse cross-sectional views of endodonticfiles.

[0161]FIG. 28 is a longitudinal cross-sectional view of a tooth with aroot canal being cleaned with a file instrument having a file formed bymachining a groove into a metal blank.

[0162]FIG. 29 is a perspective view of another embodiment of anendodontic instrument.

[0163]FIG. 30 is a partial perspective view of an endodontic filedepicting the tip of the file.

[0164]FIG. 31 is a partial perspective view of an endodontic filedepicting the tip of the file.

[0165]FIG. 32 is a partial perspective view of an endodontic filedepicting the tip of the file.

[0166]FIG. 33 is a partial perspective view of an endodontic filedepicting the tip of the file.

[0167]FIG. 34A is an enlarged perspective view of x-ray image of a rootcanal of a vital tooth without periapical rarefaction.

[0168]FIG. 34B is an enlarged perspective view of an x-ray image of aroot canal of an infected root canal without periapical rarefaction.

[0169]FIG. 34C is an enlarged perspective view of an x-ray image of aroot canal of an infected root canal with apical and periapicalresorption.

[0170]FIG. 35 is a view of a system of endodontic tools including afirst set of instruments for cleaning the operative middle portion of anoperative root canal, an optional set of instruments for improving theaccess into the apical root portion and an optional set of instrumentsfor cleaning the apical root portion.

[0171]FIG. 36A is a cross-sectional view of a tooth after the pulpchamber has been accessed and before rectification.

[0172]FIG. 36B is a cross-sectional view of the tooth shown in FIG. 36Aafter rectification and after the operative middle portion has beencleaned.

[0173]FIG. 36C is a cross-sectional view of the tooth shown in FIG. 36Aafter the apical portion has been widened.

[0174]FIG. 36D is a cross-sectional view of the tooth shown in FIG. 36Aafter the apical portion has been cleaned.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0175] The present invention relates to systems and methods for cleaningroot canals through the removal of pulp material from the root canals.The invention provides for cleaning the root canal in progressivesections from crown to apex. After the pulp chamber is opened andpreferably after further preparations, a first instrument or set ofinstruments is introduced into the root canal to clean the root canal upto the apical root portion. The apical portion is then cleaned byvarious alternative methods.

[0176] The apical portion is preferably cleaned by deliverying anirrigant into the apical portion and then removing the irrigant alongwith any debris. In some instances, an additional instrument or set ofinstruments may be optionally introduced to improve the access into theapical portion for introduction of a cannula of an irrigation tip.Alternatively, the apical root portion may also be cleaned with anotherinstrument or set of instruments.

[0177] The invention enables a dental practitioner to remove and cleanessentially all the pulp material in a root canal requiring root canaltherapy. The cleaning is achieved in a manner that is safer in terms ofover thinning of the root canal and perforations and yet requires lessinstrumentation than conventional techniques.

[0178] The techniques described herein for progressive root canaltherapy, from crown to apex, are essentially divided into distinctphases. The phases generally correspond with the particular sections orportions of the operative root canal. After the pulp chamber has beenopened to expose the anatomical root canal, during the root canaltherapy, as shown in FIG. 18, the operative root canal is considered toinclude the anatomical root canal, which extends from the pulp chamberor the floor 256 of the pulp chamber 246 to the apex 254, and theoperative coronal portion thereabove. More specifically, the operativeroot canal comprises the operative coronal portion 260, the operativemiddle portion 262 and the apical portion 264. Operative coronal portion260 essentially includes the access cavity walls. The operative middleportion 262 is the upper portion of the anatomical root canal while theapical portion 264 is the lower portion of the anatomical root canal.

[0179] The divisions of the operative root canal are distinguished fromthe nomenclature of the anatomical root canal as used to designate thesections before opening the tooth wherein the anatomical root canal isdivided into the apical portion and the coronal portion. The coronalportion of the anatomical root portion is conventionally defined as theupper portion of the anatomical root canal which terminates at the floorof the pulp chamber. However, once the pulp chamber is exposed andinstruments are introduced into the root canal the opening into thetooth should be treated as an extension of the operative root canal asit is then a continuous chamber or open tract. Accordingly, the accesswalls are considered part of the operative root canal and are designatedas the operative coronal portion or the access portion.

[0180] Apical portion 264 extends from the apex of root canal 252 up toan area of anatomical root canal 252, such that the length of the apicalportion is less than half of the length of the anatomical root canal asmeasured from the apex to floor 256. More specifically, apical portion264 is generally the bottom one-half of the anatomical root canal 252.The actual length of the apical portion varies depending on many factorssuch as the type of tooth and the age of the tooth. However, the apicalportion typically has a length in a range from about 3 mm to about 4 mmas measured from the apex.

[0181] As also indicated hereinabove, operative middle portion 262 isthe top portion of the anatomical root canal 252 and extends from floor256 down to an area of anatomical root canal 252, such that the lengthof the operative middle portion is greater than half of the length ofanatomical root canal 252. More specifically, operative middle portion262 is generally the top two-thirds of anatomical root canal 252 asmeasured down from floor 256. The length of operative middle portion canbe estimated by identifying the overall length of the root canal,typically by use of radiography, and then subtracting about 3 mm toabout 4 mm from the overall length.

[0182] As previously indicated, the three sections are treated inprimarily distinct sequential phases including: preparation of theoperative coronal portion, then cleaning or preparation of the operativemiddle portion, optionally improving access to the apical root portionand finally cleaning of the apical portion preferably by just irrigatingthe apical portion or alternatively by use of abrasive instrumentation.Examples of instruments intended for use in the cleaning the operativemiddle portion are shown in FIG. 16A and FIG. 17B. FIG. 37A and FIG. 20Bdepict insertion of a cannula of an endodontic irrigation tip into aroot canal to deliver irrigants. FIG. 21 depicts an example of a set ofoptional instruments designed for use in improving the access to theapical root portion. Examples of optional instruments intended for usein cleaning the apical portion in an abrasive manner are shown in FIGS.22-24.

[0183] The first phase or coronal phase involves exposing the pulpchamber and also preferably other steps to enhance accessibility intooperative middle portion 262 and also apical portion 264. Accordingly,the coronal or access phase is initiated by removing the top of thechamber to expose the pulp chamber. This can be achieved, for example,through the use of an instrument such as instrument 120 with bur 122 asshown in FIGS. 11A and FIG. 11B, which is preferably a diamond bur usedin conjunction with a low or high speed handpiece. However, any suitableinstrument can be utilized such as those disclosed in Italian Patent No.1,142,983 or Italian Patent No. 1,149,157, which are hereby incorporatedby reference.

[0184] After the pulp chamber has been exposed and after the pulpmaterial has been removed, a tooth appears as shown in FIG. 19A whereina molar 240 is depicted with the overhanging portions of enamel 242 anddentin 244 removed to provide access into pulp chamber 246. Pulpmaterial 250 still extends within root canal 252 from apices 254 a and254 b to the floor 256 of pulp chamber 246. Also designated at 248 isthe cementum of the tooth.

[0185] During the first phase, it is preferable to remove or reducedentinal or enamel protrusion or irregularities that may obscure orhinder access of instruments into the remaining portions of theoperative root canal. For example, dentinal shelves 266 depicted in FIG.19A are preferably reduced or rectified to provide greater access forinstrumentation during the subsequent phases. More particularly,interferences are preferably removed or minimized such that instrumentscan be inserted in the anatomical root canal in a relatively straightmanner. Accordingly, in the subsequent related drawings, such as FIG.19B, the dentinal shelf is shown removed on the canal being cleaned andas not being yet removed above the other canal. Rectification orregularization can be achieved by any suitable means. An example of ameans for rectifying dentinal shelves is set forth in U.S. Pat. No.5,642,998 and in U.S. Pat. No. 5,775,904 which were incorporated byreference hereinabove. It may also be necessary to widen the tract ofthe operative coronal root canal. Some dentists may prefer to obtaingreater access through a cuspidectomy. Note that during the root canalprocedure procedure, a rubber dam is typically used to isolate thetooth, which may require in some instances, the rebuilding of the pulpchamber walls. During this phase as well as the others, it is generallynecessary to irrigate the root canal with irrigants or a root canalconditioner/lubricant.

[0186] After the operative coronal portion has been adequately prepared,it is preferable to prepare an x-ray image of the tooth to identify thelength of the operative root canal in order to determine the preferredworking length for the instrument or set of instruments to be used inthe next phase. The preferred working length is preferably identified bysubtracting about 3 mm from the total radiographic length of theoperative root canal. The total radiographic length is preferablyderived from a radiograph made using a localizator and a long coneradiographic head.

[0187] The second phase involves cleaning or preparation of operativemiddle portion 262. It may also involve to some extent fartherrectification of the operative coronal or access portion 260 throughfurther removal of any ledges or outcroppings which prevent straight andeasy access into the operative middle portion 262. Additionally, it mayalso involve some degree of rectification of the upper region or segmentof operative middle portion 262.

[0188] An example of a set of instruments designed for cleaning theoperative middle portion is shown in FIG. 16A. The set comprises threefile instruments 200 which each comprise a handle 202 connected to afile 204 or a shaft with tines or an abrading portion. Each file 204 hasa top end 203 where the file joins handle 202. Handle 202 is connectedto top end 203 of file 204 such that movement of handle 202 also movesat least top end 203 of file 204 along a common longitudinal axis withhandle 202.

[0189] The diameter of top end 203 a is less than the diameter of topend 203 b and the diameter of top end 203 b is less than the diameter oftop end 203 c. When utilized to clean the operative middle portion of aroot canal, file 200 a is first introduced into the operative middleportion followed by file instrument 200 b and then 200 c. Accordingly,the diameter of the top end of each successive file introduced into theoperative middle portion is greater than the diameter of the top end ofeach preceding file.

[0190] Each file terminates at a tip 208 located opposite top end 203.The diameter of each tip 208 in a set of instruments is essentially thesame such that the diameter of tip 208 a is about the same as thediameter of tip 208 b and tip 208 c. For example, a set of instrumentsmay all have tip diameters of about 0.10 mm. A set may also be designedsuch that the instrument intended to be inserted first has a tipdiameter of about 0.10 mm while the other instruments in the set have atip diameter of about 0.13 mm. A set with slightly different tipdiameters, such as a set of three or four instruments with respectivetip diameters of 0.10 mm, 0.10 mm, 0.13 mm and 0.13 mm, and in any eventnot exceeding 0.15 mm is still considered to have substantially constanttip diameters within the set as the difference in size is very minor andthe diameters do not sequentially increase for each instrument. In analternative embodiment, the tip diameter may vary between instruments ina set such that, for example, the tip diameter of each sequentiallyinserted file is progressively larger. As shown in FIG. 16B, which is anenlarged view of tip 208 b, the tips are generally sharp and areconfigured for at least minimal cutting capability.

[0191] Each operative middle portion file 204 is configured with asuitable abrading portion 209 along most or all of the length of eachfile. The file is preferably configured such that the abrading portion209 extends along its entire length as shown in FIG. 16A, however, thefiles may also have a smooth upper shank portion. Abrading portion 209is at least the outer edge of the file 204. The abrading portion of thefiles in FIG. 16A are formed by twisting a blank such as a rectangularblank.

[0192]FIG. 17A depicts another set of file instruments 210 which havefiles with a different abrading portion compared to the abrading portionof the files of file instruments 200. The files 214 have abradingportions 219 that were formed by machining the files to have knurledsurfaces. Abrading portion 219 as well as abrading portion 209 and theother abrading or cleaning surfaces disclosed herein are examples ofmeans for abrading the walls of the root canal or root canal surfaces.

[0193]FIG. 17B is an enlarged view of tip 218 a which is shown with amore rounded configuration than tip 208 b such that the tip hasessentially no cutting capability. FIG. 18B shows another embodiment ofa suitable tip which is designed for more aggressive cutting than tip208 b at least as the tip is pushed downward.

[0194] Since the tip diameters are essentially equal and since thediameter of the top end of each successive file introduced into theoperative middle portion is larger than the diameter of the top end ofthe preceding file, the taper of each successive file in the set islarger than the preceding file. For example, the taper may range from0.04 to 0.13 and increase in increments for each successive file. Eachsuccessive file accordingly has an increased surface area for cleaningthe root canal. Additionally, as files are inserted into a root canalwith larger and larger tapers, the rigidity of the upper half of eachsuccessive file also increases. The increase in rigidity is, however,minimized by maintaining the tip of each file at about the samediameter. The flexibility of the lower half remains essentiallyconstant. The rigidity in the upper half is used to remove interferencesand to properly rectify the operative coronal portion 260 and theoperative middle portion 262. The consistency in rigidity at the upperhalf is useful since the lateral perimetrical force applied to thehandle is primarily transferred to its upper half or at least the partclosest to the handle, which is the strongest part of the file.

[0195] By properly selecting a combination of factors including thediameters of the files at the top ends and at the tips as well as thematerial used to form the files, the files are designed such that eachfile has sufficient flexibility to be flexed or curved to urge theabrading portion against the surfaces or walls of the root canal andsufficient rigidity to apply pressure against the surfaces of the rootcanal as the abrading portion of the file is urged against the surfacesof the root canal and simultaneously moved in a cleaning motion.Additionally, the files have adequate resilience to avoid beingsubstantially deformed as the file instrument is flexed or curved tourge the abrading portion against the surfaces of the root canal.

[0196] The file can be formed from any suitable material. In forming asuitable file, the material is preferably selected in view of thedimensions and design, to yield a file having the desired propertieswith respect to flexibility, resilience and/or rigidity as set forthabove. The preferred material for forming files used to clean theoperative middle portion of root canals is stainless steel. Other metalscan also be used such as nickel/titanium; however, it may be necessaryto design the files to have larger diameters than files formed fromstainless steel when using nickel/titanium as nickel/titanium tends tobe more flexible than steel. Alternatively, the files can be formed fromsuitable non-metal materials, such as a plastic.

[0197] When the files are formed from stainless steel or a material withcomparable properties, the top end diameter of each file, where theabrading portion terminates, may range from about 0.25 mm to about 2 mm.However, the diameter will more typically range from about 0.3 mm toabout 1.8 mm and most typically from about 0.4 mm to about 1.5 mm.Additionally, when the files are formed from stainless steel or amaterial with comparable properties, the tip diameter of each file mayrange from about 0.06 mm to about 0.4 mm. More typically, however, thetip diameter will range from about 0.08 mm to about 0.15 mm and mosttypically from about 0.08 mm to about 0.1 mm.

[0198] The length of each file in the set used to clean the operativemiddle portion depends on the length of the tooth being cleaned. Moreparticularly, after identifying the length of the root canal from anx-ray image, the length of the file to be used in the operative middleportion is determined by subtracting 3 mm from this identified length ofthe root canal. This length is typically between about 15 and about 20mm, however, longer files, such as a 25 mm long file, are typicallyrequired for canine teeth. To provide for the different root canalconfigurations which may be encountered, it is preferred to have fileswith lengths ranging from about 8 mm to about 35 mm. However, files withlengths ranging from about 10 mm to about 30 mm will be most utilizedand files with lengths ranging from about 14 mm to about 26 mm will bethe most frequently utilized.

[0199] After identifying the combined length of the operative middleportion and the operative coronal portion and after removing theoverhanging enamel 242 and dentin 244, the practitioner selects a fileinstrument or a set of file instruments as shown in FIG. 16A or FIG. 17Awith an appropriate file length. In an embodiment that utilizes nostops, the appropriate length corresponds to the combined length of theoperative middle portion length and the operative coronal portion. Asshown in FIG. 19B, file 204 a of file instrument 200 a is then insertedinto root canal 252 down through operative middle portion 262 withoutextending substantially into apical portion 264. Each file 204 of eachfile instrument 200 in the set of instruments shown in FIG. 16A has alength that is only sufficient to enable the file to contact theoperative middle portion and the operative coronal portion of the rootcanal. Accordingly, a file instrument such as file instrument 200 a or aset of file instruments such as 200 a, 200 b and 200 c comprises a firstendodontic instrument means for anatomically removing and anatomicallycleaning essentially all pulp material from the operative middle portionwithout significantly extending into the apical root portion.

[0200] The file length of files 204 enables a practitioner toaggressively clean the operative middle portion without worrying thatthe instrument will overly thin the root canal, perforate the apex orthat cleaning will cause extrusion of material through the apex. Anotherbenefit of cleaning the operative middle portion first is that theapical portion is then generally more accessible and easily cleaned.Additionally, since instruments are selected for use in cleaning theoperative middle portion which have files lengths that do not permitentry into the apical portion, the likelihood of jamming or breaking atip of an instrument while working in the confined space of the apicalportion is prevented.

[0201] By instrumenting in the operative middle portion and theoperative coronal portion before the cleaning the apical portion, thepractitioner can use an instrument that is relatively flexible comparedto the conventional instruments. As shown in FIG. 19C, which is across-sectional view taken along cutting line 19C-19C of tooth 240 inFIG. 19B, file 204 a of file instrument 200 a is sufficiently flexibleto be flexed against any surface of operative middle portion 262 oroperative coronal portion 260 and yet is sufficiently rigid to remainflexed against the surface during a cleaning motion such as alongitudinal motion, a rotational motion or a reciprocating rotationalmotion. The file is also sufficiently resilient that substantialdeformation of the file does not occur due to the forces experiencedduring cleaning of the pulp material from the root canal.

[0202] File instrument 200 a is shown in FIGS. 19B and 19C being movedin a longitudinal movement or up and down movement as well as beingrotated while file 204 a is flexed or arched to urge the file againstthe root canal surfaces. As shown, the configuration of the files usedto clean the operative middle portion, and preferably the operativecoronal portion as well, enable a practitioner to move the files aroundthe perimeter or from side to side to contact the perimeter. Further,since the file is moved around the perimeter, the file has more than onecenter of motion during cleaning of the operative middle portion of theroot canal, such as a pivot point or center of rotation, as the tip ofthe file or at least a part of the abrading portion does not generallyremain primarily in one position. This is in sharp contrast to prior artmethods which limited the practitioner to essentially rotating aconically shaped file to yield a cone shaped borehole.

[0203] Due mainly to the configuration of the files, each file is ableto flex such that its abrading portion is urged against root canalsurfaces while the instrument is rotated and moved in a cleaning motion.Accordingly, the contours of the operative coronal portion and theoperative middle portion can be used during their cleaning by apractitioner as a guide for the movements of the instruments as thefiles are pushed against the surfaces of the root canal andsimultaneously moved around the perimeter or periphery of the root canaluntil the practitioner has reached the beginning location of thecleaning and shaping process. For example, in root canals that areprimarily noncircular, the files can be urged along one side and thenalong the next side wall in a manner such that the resulting cleaned andshaped root canal is generally widened but still primarily noncircular.In other words, there is essentially no borehole that obviouslycorresponds to the shape of the file as the instruments have been movedin conformance to the anatomical shape of the operative middle portion.

[0204] Due to the ability to move the file as discussed, the anatomy ofthe root canal remains substantially unaltered despite the cleaning ofessentially all pulp material from the operative middle portion. Theunderstanding that the final anatomy is guided by the shape of theoriginal anatomy enables a practitioner to more confidently urge a filesuch as file 204 a against all surfaces of root canal 252 andaggressively clean all of the surfaces of operative middle portion ofthe root canal since the likelihood of overly thinning the root canal orcausing lateral perforations as shown in FIGS. 15A-C and FIG. 15E isdiminished. The assurance of the safety of the methodology is furtherbolstered by a general knowledge of wall thickness variations.

[0205] Another advantage of the configuration of operative middleportion instruments, such as file 204 a shown in FIGS. 19B and 19C, isthat the file can simultaneously abrade both operative coronal portion260 and operative middle portion 262. The files can simultaneouslyabrade both portions as each file has an abrading portion along theentire length of the file. A primary benefit of simultaneously abradingboth portions is the ability to further straighten the operative coronalportion while cleaning the operative middle portion.

[0206] Use of files in the operative middle portion which have anabrading portion along their entire length is in contrast to filesformed in accordance with ISO standardization. ISO standardized fileshave abrading portions of up to 16 mm and the remainder of the file is asmooth shank. Examples of such files are shown in FIGS. 13A-B and 14A-B.Since such conventional files are inserted down to the apex, it isgenerally not possible to abrade any portion beyond the anatomical rootcanal. Since such conventional files frequently fail to removeinterferences extending from the access or root chamber above theanatomical root canal, as shown in FIG. 13A, the instrument must bendaround the interferences, thereby further increasing the likelihood ofwall perforations, overthinning and failing to clean significantportions of the canal. It especially increases the likelihood ofiatrogenic modifications resulting from the tip of the file.

[0207] The instruments in the sets shown respectively in FIG. 17A and inFIG. 18A at 210 a-c and at 220 a-d are each depicted with a stop 140.Stops such as stop 140 may be used to ensure that the length of theportion of the file inserted into the tooth is such that the file doesnot extend significantly into the apical root portion. FIG. 19D depictsthe use of stop 140 on instrument 220 a. The advantage of using such astop is that less sets of instruments are needed in order to have a setthat can be utilized in teeth of varying lengths. Note that while stopsare shown which have a thickness of about 1 mm, the stops may havevarying thickness. Also, the stops may also be positioned such that oneor more stops are positioned adjacent to the handle such that movementis not possible since the stops already abut the handle. For example, inFIG. 18A two stops are positioned on shank portion 226 a of file 224 a.One of the stops has a thickness of 2 mm while the other has a thicknessof of 1 mm as shown respectively at 141 and 140. Note that stop 141abuts handle 222 a to prevent any possible movement. All of the stopdisclosed herein are examples of stop means for limiting the operativemiddle portion instrument means to insertion into the operative coronalportion and the operative middle portion.

[0208] When a stop is used, the length of the root canal from an x-rayimage is first identified and then the length of the root canal abovethe apical root portion is determined by subtracting 3 mm from thisidentified length of the root canal. An instrument is then selected thathas a length that is slightly longer than the determined length of theroot canal down to the apical portion. Note that this determined lengthis the combined length of the coronal portion and the operative middleportion.

[0209] It may also be advantageous to use a stop such as stop 140 tomore easily flex the file against the root canal surfaces. Moreparticularly, using an instrument with a stop alters the curvature ofthe file since the portion above the file is also flexed. This resultsin a different flexed configuration or pivot point so that greatestpressure is applied at a higher part of the root canal than when aninstrument is used without stops. The desirability of applying pressurein such a manner depends on the particular tooth. Note however that ifan instrument is used without a stop as in FIG. 19B and FIG. 19C theportion of the file that is flexed against the root canal can also beused to abrade sections thereabove by merely moving the file upward asit is flexed.

[0210] Although the file instruments used to clean the operative middleportion, can be manually moved, they are preferably used in conjunctionwith an instrument designed for movement of endodontic file instrumentssuch as a conventional dental handpiece instrument. An example ofpreferred handpiece instrument is disclosed in U.S. patent applicationSer. No. 09/425,849 entitled Systems for Incrementally Adjusting theWorking Length of Endodontic Instruments and in U.S. patent applicationSer. No. 09/425,857 entitled Incrementally Adjustable EndodonticInstruments which were filed on Oct. 22, 1999 by Dan E. Fischer and areowned by Ultradent Products, Inc. Ser. No. 09/425,849 and Ser. No.09/425,857 are hereby incorporated by reference. The handpiece 500 shownin FIG. 19D and in FIG. 19E at 500 corresponds with the handpiecesdisclosed in Ser. No. 09/425,849 and Ser. No. 09/425,857. Handpiece 500has a head 600 with a head element 610 that holds a chuck 700. One ofthe advantages of handpiece 500 is that rim 614 of head element 610 isessentially coplanar with any bottom surfaces of head element 610. Thisessentially coplanar configuration is particularly useful since rim 614is used as a stop as it is rested on the coronal surface of tooth 240′.The ability to use rim 614 as a stop eliminates the need for rubberstoppers. Although, it is not necessary to use a stop when usinginstruments adapted for use with the handpiece disclosed in theabove-identified applications, a stop is shown being used in FIG. 19D inorder to illustrate the use of stops with handpieces in general.Accordingly, it is understood that the instruments disclosed herein canbe used with any conventional handpiece.

[0211] When rotated by a handpiece, the file instrument such asinstrument 220 a shown in FIG. 19D can be continuously rotated in onedirection only or the file instrument can be rotated in a reciprocatingmotion such that the file instrument rotates for example, clockwise forhalf of a revolution and then counterclockwise for half a revolution. Areciprocating motion is preferred as such motion enables the file toalternately engage material 250 and the walls of the operative middleportion of the root canal in a manner that removes material 250 and tothen rotate in the opposite direction such that the file lessaggressively engages material 250 and the operative middle portionwalls, depending on the file design. Accordingly, rotating fileinstrument 220 a in a reciprocating motion minimizes breakage of file224 a when file 224 a encounters a surface that prevents rotation offile instrument 220 a in a direction that enables cleaning and removalof material 250.

[0212] Handles 202 a-c, 212 a-c, and 222 a-d are latch-type handlesdesigned for coupling with a handpiece. Note that although instrument200 a has a latch-type handle, a handpiece is not depicted in FIG. 19Band FIG. 19C being used to move the file instrument, in order tooptimally view the movement of the instrument. An example of a handleadapted for manual manipulation is shown in FIG. 28 at 312. Movement ofthe file instrument with a handpiece is preferred as hand milling ismore difficult and time consuming. A file instrument can also bevibrated to clean the coronal portion and the operative middle portion.

[0213] File instrument 220 a shown being utilized in cleaning thecoronal portion 260 and the operative middle portion 262 of tooth 240′in FIG. 19D is part of a set of instruments is depicted in FIG. 18A at220 a-d. File instruments 220 a-c have the same dimensions asinstruments 200 a-c and are similarly configured except that each offile instruments 220 a-c has a shank portion 226. The shank portions 226a-d at respective top ends 223 a-d provide for easy movement of stops140. As previously indicated in reference to the set of instrumentsdepicted in FIG. 16A at 200 a-c, the instruments used to clean thecoronal portion and the operative middle portion may be configuredwithout a smooth shank portion. If the instruments have a shank portionit is preferably about 2 to about 4 mm in length and is preferably about4 mm. Note that the instruments in FIG. 17A depict relatively shortshank portions that are about 2 mm in length while the instruments inFIG. 18A depict longer shank portion that are about 4 mm in length. Theshank portions depicted in FIG. 17A, FIG. 18A, FIGS. 18C have a slighttaper; however, the shank portions may also be non-tapered like theshank portions of the instruments shown in FIG. 23 and in FIG. 24.

[0214] The set of instruments shown in FIG. 18A also includes anaggresive abrasion instrument 220 d. After the operative coronal portionand the operative middle portion have been cleaned and shaped throughthe use of instruments such as abrasion instruments 220 a-c then theroot canal can be more aggresively shaped with instrument 220 d.

[0215] Like the other instruments in the set, instrument 220 d has afile 224 d with a shank portion 226 d at its top end 223 d; however, thefile 224 d has a unique abrading portion 229 d. File 224 d, moreparticularly abrading portion 229 d, has an abrasive upper section 225 dfor aggresive abrasion and a lower section 227 d that is relatively lessabrasive than the upper section. The upper section 225 d has abrasiveparticles positioned thereon while the lower section 227 d is not coatedwith abrasive particles but is twisted or fluted. File 224 d is formedby twisting the lower section and positioning an abrasive on part of thesmooth or non-fluted upper section of the file above the lower flutedsection. All of the smooth or non-fluted upper section may be coated sothat there is no shank portion or a portion may be left uncoated so thatthere is shank portion as shown in FIG. 18A at 226 d.

[0216] The advantage of using an instrument with a file having an uppersection with abrasive particles such as instrument 220 d as shown inFIG. 18A or instrument 220 d′ as shown in FIG. 18B is that the coronalportion and the top of the operative middle portion can be moreaggresively shaped while shaping the bottom of the operative middleportion less aggresively. The usefulness of an instrument such asinstrument 220 d to clean or shape with greater abrasiveness at itsupper half and less abrasiveness at its lower half is depicted in FIG.19E which is a cross-sectional view of tooth 240′ with instrument 220 dbeing moved by chuck 700 of endodontic handpiece head 600. The upperabrasive particle coated section 225 d enables the removal or reductionof dentinal or enamel protrusions or irregularities such as dentinalshelves shown at 266 in FIG. 19D that may obscure or hinder access ofinstruments into the operative root canal. In many instances, use of aninstrument such as instrument 220 d eliminates the need forrectification of such protrusions with a rectification instrument.

[0217] Note that tooth 240′ shown in FIG. 19E is nearly identical totooth 240 shown in FIG. 19C, the only difference is that tooth 240′ doesnot have an outcropping of dentin to divide the canal like thatidentified as 244 in FIG. 19C. Tooth 240′ appears without such anoutcropping to clearly illustrate that the depicted movements of theinstruments in FIG. 19C and in FIG. 19E occur in accordance with thepresent invention in the operative middle portion of all teeth. Statedotherwise, such movements enable the file to follow the contours of theroot canal and are utilized in the operative middle portion of all rootcanals.

[0218] The abrasive particles are preferably diamonds. The application,impregnating, coating or attachment of the diamond coating may beachieved by any conventional method. For example, the abrasive particlesmay be electrolytically applied, plated, sintered, bonded with adhesivesor impregnated into the surface of the smooth part of the file. Examplesof preferred methods of positioning abrasive particles includes formingthe coating by electro-deposition or by direct or indirect sputtering.

[0219] Although, diamond is the preferred material other materials maybe optionally used instead of or in addition to diamond. Examples ofsuitable materials for use as abrasive particles include: carborundum™or other suitable refractories of silicon carbide, fused alumina andother materials; aluminum oxide; natural aluminum oxide such ascorundum; alumina ceramics; glass; silicon dioxide or silica; siliconcarbide; boron nitride; and other comparably hard materials.

[0220] The abrasive particles may form a coating, layer or covering withany suitable thickness and the particles may have any suitable averagesize. More particularly, the thickness of the abrasive particle coatingis preferably in a range from about 100 μm to about 700 μm, morepreferably about 200 μm, and most preferably about 500 μm. A preferredaverage particle size is in a range from about 30 μm to about 350 μm. Amore preferred average particle size is in a range from about 50 μm toabout 250 μm.

[0221] Files with abrasive particle coated upper sections alsopreferably have a smooth shank portion below the handle. The smoothshank portion preferably has a length of about 2-4 mm. The upperabrasive particle coated section is preferably no greater than abouthalf of the length of the file extending from the handle and is morepreferably less than half of the length of the file extending from thehandle. Instruments having an abrading portion with an upper abrasiveparticle coated section and a lower less abrasive section are preferablyconfigured such that the length of the upper abrasive particle coatedsection is about the same as the lower less abrasive section. Thelengths of such upper abrasive particle coated sections are accordinglyin a range from about 4 to about 10 mm in length and are preferably in arange from about 4 to about 8 mm in length.

[0222] Lower fluted section 227 d is an example of a lower less abrasivesection. The lower less abrasive section may also be configured like theknurled surface of abrading portions 219 or any other surface whichabrades less aggresively than the use of abrasive particles. The lowersection may also alternatively be smooth like the shank portion andterminate at a tip so that it has essentially no abrasive ability.

[0223] The file of the instrument preferably has the abrasive particlecoating on only the upper section of its abrading portion as shown inFIG. 18A, FIG. 18B and in FIG. 19E; however in some embodiments, theentire abrading portion may be coated with abrasives. Additionally, theupper section that has abrasive particles may also be twisted or flutedas shown in FIG. 27J so that the entire abrading portion is twisted orfluted while only the upper section is covered with abrasive particles.Similarly, the entire abrasive portion may be configured as shown inFIG. 17A with a knurled surface while the upper section is covered withabrasive particles. Further, the abrading portion may have anyappropriate configuration and have an upper portion with abrasiveparticles that enable more aggresive abrasion in the operative coronalportion of the root canal and in the top region or segment of theoperative middle portion of the root canal.

[0224] An instrument such as instrument 220 d or 220 d′ is preferablypart of a set of instruments such as the sets shown in FIG. 18A or 18Bsuch that the set includes at least one abrasion instrument and oneaggresive abrasion instrument. The set of instruments shown in FIG. 18Bincludes only the last two instruments of the set shown in FIG. 18A.Note that the only difference depicted between instrument 220 d andinstrument 220 d′ is that instrument 220 d has a smooth tip 228 d forless aggresive cutting while instrument 220 d′ has a pointed tip 228 d′.Pointed tip 228 d is shown in greater detail in FIG. 18C.

[0225] Advantages of using a set such as instruments 220 c-d′ instead ofa larger set such as instruments 220 a-d is that the set is lessexpensive and is simpler to use. However, it may also be preferable touse a set with three, four or more instruments to clean the operativecoronal portion and the operative middle portion with very gradualincreases in rigidity so that the aggresiveness of the abrading isgradually increased as the instruments are sequentially utilized.

[0226] As indicated above, while instruments 220 a-c have shank portionsthese instruments have the exact same dimensions as instruments 200 a-c.Accordingly, the files of instruments 220 a-c all have essentially thesame length and tip diameter and also have sequentially larger top enddiameters and tapers. Aggresive abrasion instruments 220 d and 220 d′,however, are each shown with a file having a length, tip diameter, topend diameter and taper that is essentially the same as that of file 224c. Although, the file of the aggresive abrasion instrument preferablyhas the same dimensions as the instrument previously inserted into theroot canal, other configurations may also be utilized. For example, theaggresive abrasion instrument may have a larger top end diameter and alarger taper than the file of the instrument introduced previously inthe sequence or a smaller top end diameter and a smaller taper.

[0227] Instruments such as instruments 220 d or 220 d′ may be used aloneor as part of a set to remove and clean essentially all pulp materialfrom the operative coronal portion and the operative middle portion.Instruments such as 220 d or 220 d′ as well as sets that includes suchinstruments are additional examples of first endodontic instrument meansfor anatomically removing and anatomically cleaning essentially all pulpmaterial from the operative middle portion without significantlyextending into the apical root portion.

[0228]FIG. 19F shows a cross-sectional view corresponding to the x-rayview after pulp material 250 has been removed from the operative middleportion 262 of root canal 252 a and after the surfaces of root canal 252a have been shaped to yield shaped surfaces 268 a of the root canal.FIG. 19G is a longitudinal cross-sectional view taken along cutting line19G-19G of tooth 240 in FIG. 19F which clearly shows that essentiallyall pulp material has been removed and cleaned from operative middleportion 262.

[0229] Removal of pulp material 250 from operative middle portion 262removes the majority of bacteria in the pulp canal since the majority ofbacteria in an infected root canal is typically located in the operativemiddle portion. Not only is the greatest volume of bacteria in theoperative middle portion but it is also believed that the concentrationis greater in the operative middle portion. Since a certain minimumthreshold must generally be reached for complications to arise due tomicrobial presence in a root canal, removal of the pulp material in theoperative middle portion significantly reduces the likelihood of suchcomplications.

[0230] By removing the majority of bacteria before cleaning the apicalportion there is also less likelihood of exposing the surrounding tissueto bacteria due to overly thinning the root canal, perforation orextrusion of material from the canal. The greatest likelihood for theoccurrence of complications such as over thinning of root canal walls,perforation or extrusion of material from the canal is in the apicalportion. The apical portion is the most likely site for suchcomplications as apical portions are more complex and delicate comparedto the operative middle portions of teeth. Since such complications aremost likely to occur in the apical portion, it is highly beneficial tohave the material removed from the operative middle portion in order tominimize the amount of material that can come out of the root canal tocause problems. For example, in the event of an apical extrusion farless septic material may be expressed during instrumentation inaccordance with present methodology than if the apical extrusionocccured as a result of cleaning in accordance with conventional methodswherein files are inserted to the apical portion before cleaning theoperative middle portion. As a result, removal of the majority ofbacteria before cleaning the apical portion increases the likelihood ofsuccessful root canal therapy in several ways compared with conventionalmethods.

[0231] To minimize the possible introduction of bacteria, it ispreferable to utilize a kit such as the kits disclosed in U.S. Pat. No.5,967,778 entitled “Containing Device For Dental Tools with FoamSupporting Materials”, the disclosure of which is hereby incorporated byreference. U.S. Pat. No. 5,967,778 issued to Francesco Riitano and isowned by Ultradent Products, Inc. The kits preferably support a set ofseveral instruments with identical lengths positioned to be easilygrasped and preferably in an antimicrobial solution.

[0232] It should be noted that when there is an atresic root canal, itis preferable to use EDTA in a hydrosoluble gel and leave thecomposition in the canal for a few minutes. Similarly, for necroticcanals, it is advisable to work in a sodium hypochlorite saturatedenvironment. For canals with living pulp, it is advisable to work in anenvironment saturated with 10% hydrogen peroxide.

[0233] As previously discussed, the majority of bacteria in an infectedroot canal is typically located in the operative middle portion.Accordingly, it has been found that after the operative middle portionhas been cleaned in an abrasive manner effective root canal proceduresare completed by cleaning the apical portion without abrading the apicalportion. More particularly, after removing and cleaning essentially allpulp material from the operative middle portion of an operative rootcanal in conformance with the anatomical shape of the operative middleportion by flexibly moving an instrument within the operative middleportion, the root canal procedure can be effectively completed by merelyirrigating the apical portion of the root canal and then removing theirrigant and debris. This eliminates the possibility of exposing thesurrounding tissue to bacteria due to overly thinning or perforating theapical portion of the root canal and minimizes the possibility ofextrusion of material from the canal. Since such complications typicallyoccur during abrasive instrumentation within the apical portion due tothe delicate and complex structure of the apical portion, theelimination of the need for abrasive instrumentation in the apicalportion is highly advantageous. Further, this methodology isparticularly advantageous in light of the prior cleaning of the rootcanal above the apical portion.

[0234] Another benefit of cleaning the apical portion by irrigating theapical portion with an irrigant and then removing the irrigant anddebris from the apical portion, is the reduction in the number ofinstruments needed to complete the procedure. More particularly, sinceinstruments adapted for abrading the apical portion are not necessarybut are optionally used, the total instruments used in performing rootcanal procedures is reduced.

[0235] In addition to cleaning the apical portion, irrigation is used tomaintain the smear layer in solution within the apical portion, therebyavoiding smear layer accumulation. Additionally, it is useful tomaintain the debris derived from cleaning the root canal in suspensionto avoid filling the apical portion of the root canal with a plug. Ifthe apical portion becomes filled, there is an increased likelihood thatthe progression may be prevented or that debris may be pushed out of thetooth.

[0236] In addition to conventional irrigation devices, a preferredirrigation device is shown in FIG. 20A and FIG. 20B which is a syringe790 coupled to an irrigation tip 720. Such irrigation devices,particularly the angled irrigation tips, are disclosed in greater detailin U.S. Pat. No. 6,079,979 entitled Endodontic Irrigator Tips and Kitswhich issued to Francesco Riitano and is owned by Ultradent ProductsInc.; the disclosure of which is hereby incorporated by reference. Whilesuch irrigation devices are preferred, any conventional irrigation tipand associated delivery device such as a syringe may be utilized.

[0237] Note that due to the angled configuration, as shown in FIG. 20Aand FIG. 20B, a practitioner is readily able to place the cannula 760extending from neck 740 of angled tip 720 into a root canal 782 of apatient's tooth 780 while holding a syringe 790 coupled to tip 720 at anangle with respect to the patient's mouth. This angled configurationenables the practitioner to more easily insert cannula or needle 760into a root canal and to move the tip within the root canal.

[0238] As shown, the practitioner is able to strategically, convenientlyposition stop end 744 on the rim of the occlusal surface of a crown andorient cannula 760 in a controlled manner within root canal 782. Notethat neck 740 has a stop end 744 with a distal flat face 746 which isconfigured to act as an integral stop to prevent penetration into theroot canal 782 of endodontic irrigator tip 720 beyond the length of theportion of cannula 760 extending from stop end 744 of neck 740.

[0239] The working length of cannula 760 is the portion of cannula 760extending past stop end 744 of neck 740. By using an irrigator tiphaving a cannula with the appropriate working length and a neck 740having an integral stop end 744, the practitioner is able to avoidapical perforations. For example, as shown, a tip may be selected with acannula length which extends within about 1 millimeter above the apex784, while stop end 744 prevents cannula 760 from penetrating too far.This permits the calculated delivery of fluid all the way to apex 784without perforating apex 784. Thus, because of stop end 744 and acannula 760 having an appropriate working length, the practitioner canconfidently place cannula 760 in close proximity to apex 784 withoutperforating apex 784. Note that it is preferred to slowly withdrawcannula 760 while deliverying the irrigant. Although, tip 720 ispreferred, other conventional endodontic irrigator tips may also beutilized and conventional stops may also be utilized.

[0240] Another preferred irrigation tip is the Endo-Eze® irrigator tipsold by Ultradent Products, Inc which has a straight cannula or needle.Examples of suitable Endo-Eze® irrigator tip include those which have a27 gauge cannula (0.40 mm out diameter), 30 gauge cannula (0.30 mm outerdiameter) and a 31 gauge (0.25 mm outer diameter). In somecircumstances, larger needles may be used. In any event, the needle orcannula is preferably sufficiently small to avoid binding within thecannula and also to enable backflow for flushing the apex.

[0241] The irrigator tips and other suitably shaped narrow tubulardevices such as pipettes, are referred to herein as apical portioncleaning instruments. The irrigator tips disclosed herein and othersuitably shaped narrow tubular devices, are examples of means forcleaning the apical root portion, after the pulp material has beenessentially removed from the operative middle portion. Morespecifically, the irrigator tips are examples of means for cleaning theapical root portion by deliverying an irrigant into the apical rootportion.

[0242] In addition to syringes, such irrigator tips may be coupled to aStropko device such as the delivery device disclosed in U.S. Pat. No.5,378,149 issued to John J. Stropko which is hereby incorporated byreference. Syringes and the Stropko device are examples of deliverydevices. These same devices are examples of irrigant delivery deviceswhen coupled with an irrigator tip that enables the delivery devices toeasily access the root canal. While these irrigant delivery devices areparticularly useful when cleaning the apical portion, note that all ofthese irrigant delivery devices may also be used in irrigating the canalat any appropriate time during the root canal procedure. Note thatsyringes and other delivery devices such as a Stropko delivery deviceare examples of means for deliverying irrigants and/or removingirrigants and any remainig debris via the irrigator tip or means forcleaning the apical root portion.

[0243] Pipettes are a less preferred alternative to the use ofirrigation tips as apical portion cleaning instruments to deliverirrigants into the root canal. Such conventional pipettes are well knownin endodontistry and are used to deliver irrigants by squeezing part ofthe pipette. The pipettes may be prefilled or used with a separatereservoir or container of lubricant. A pipette is an example of anintegral irrigant delivery device while an irrigator tip coupled to asyringe or a Stropko device is an example of a separable irrigantdelivery device. Such integral irrigant delivery devices are additionalexamples of means for cleaning the apical root portion or morespecifically, means for cleaning the apical root portion by deliveryingan irrigant into the apical root portion.

[0244] These same irrigant delivery devices are typically used to removethe irrigant and any remaining debris. For example, the syringe may beused to aspirate the irrigant and any remaining debris out of the apicalportion. Similarly, a pipette may apply appropriate suction to removethe irrigant and any remaining debris. The endodontic irrigator tip mayalso be coupled to other conventional aspiration devices. Other irrigantremoval devices include conventional paper points. When the irrigant anddebris have been removed, the tooth appears as shown in FIG. 20B at 780.

[0245] Although, the irrigant preferably is capable of dissolving ordisrupting soft tissue remnants to permit their removal, the irrigantmay be any suitable liquid such as water or various alcohols. Moreparticularly, although some degree of debridement is preferred, anyfluid may be used to flush debris from the root canal. General examplesof appropriate irrigants include hydrogen peroxide, primarily for use inthe canals of living teeth, or sodium hypochlorite, primarily for thecanals in necrotic teeth. The preferred irrigant is the aqueous sodiumhypochlorite solution sold as ChlorCid® by Ultradent Products, Inc whichcontains about 2.5-3% NaOCL. The irrigant may also be a chelator orcalcium remover such as EDTA solutions or citric acid solutions. Apreferred chelator is sold as File-Eze® by Ultradent Products Inc. whichis a 19% EDTA water soluble viscous solution. File-Eze® is a preferredchelator as it is also a lubricant. Another example of a commerciallyavailable chelator is the Pulpdent EDTA solution sold by Pulpdent Inc.

[0246] In some circumstances, it may be necessary to improve the accessinto the apical root portion before cleaning the apical root portion ofthe root canal. More particularly, it may be beneficial or necessary towiden the tract of the root canal to provide access for thin irrigationneedles. This may be achieved by widening the transition between theoperative middle portion and the apical portion or by widening theentire apical portion such that a thin irrigation needle can access theapical portion as needed. Thin irrigation needles typically have adiameter no smaller than about 0.30 mm so it may be necessary toincrease the diameter of portions of the root canal up to about 0.35 mmor even up to about 0.40 mm, particularly within the region of theboundary between the operative middle portion and the apical rootportion. Note that the diameter need only be slightly larger than a thinirrigation needle in order to provide adequate access. Improving accessinto the apical portion not only enables such irrigation needes to havemove as needed, it also reduces the likelihood that the thin irrigationneedes will be blocked.

[0247] The diameters of many root canals within the region of theboundary between the operative middle portion and the apical rootportion and even within the apical portion are alreadly large enough toenable irrigation needles to deliver irrigants as far as is necessary.However, even though it is preferred not to widen the diameter withinthe apical portions or even the tops of the apical portions, it is oftennecessary to do so. Refer to Tables 2 and 3 in Example 1 for someaverage root canal diameters as measured 2 mm from the apex of each rootcanal. In Table 2 and Table 3, the largest average diameter in theapical portion for a particular type of tooth measured in the samplingwas 0.54 mm while the smallest average was 0.18 mm. Note that the tipdiameter of operative middle portion instruments, as indicatedhereinabove, typically range from 0.06 mm to 0.40 mm, more typicallyfrom about 0.08 mm to about 0.15 mm and most typically from about 0.08mm to about 0.1 mm. In light of the apical portion diameters that arelikely to be encountered, as indicated in Table 2 and Table 3, and thetip diameters of the instruments used to clean the operative middleportion just above the apical portion, it is apparent that widening isoften necessary inorder to enable irrigation needles to adequatelydeliver irrigants.

[0248] It is not necessary for the entire apical portion to be widenedup to about 0.35 mm or about 0.40 mm; just enough of the apical portionshould be widened so that the irrigants can be delivered as needed.However, the length of files used to widen the apical portion ispreferably sufficient to at least approximately reach the apex.Accordingly, the top of the abrading portion may be flared to enable theupper area of the apical portion to be widened up to about 0.40 mm whilethe tip diameter which is at or near the apex is preferablysignificantly smaller. Note that in addition to abrading at least thetop of the apical portion, it may also be necessary to widen thediameter at the region of the base of the operative middle portion withthe widening at the top of the apical portion.

[0249] Note that before widening the apical portion of the root canal,it is preferable to make a predetermination of the desired diameter.This predetermination is preferably made in light of average diameters,wall thicknesses, etc. for the particular root canal being cleaned. Asindicated hereinabove, Table 2 and Table 3, hereinbelow in Example 1,provide a sampling of such morphometric data.

[0250] An example of an optional set of instruments designed forimproving the access into the apical root portion is shown in FIG. 21.The set comprises four file instruments 270 a, 270 b, 270 c and 270 d.Each file instrument comprises a handle 272 connected to a file 274.Each file 274 has a top end 276 where the file joins handle 272. Whenutilized to widen the access into the apical root portion of a rootcanal, file 270 a is first introduced followed sequentially by file 270b, 270 c and then 270 d. Each file terminates at a tip 278 locatedopposite top end 276. A file instrument such as file instrument 270 a ora set of file instruments such as 270 a, 270 b, 270 c and 270 dcomprises an endodontic instrument means for optionally, improvingaccess into the apical root portion after the pulp material has beenessentially removed from the operative middle portion by the firstendodontic instrument means.

[0251] Each file 274 of the file instruments designed for improvingaccess to the apical root portion of a root canal is configured to havean abrading portion 279 along at least a portion of the length of file274. The entire length of each file 274 can be configured with anabrading portion 279, however, abrading portion 279 preferably extendsfrom tip 278 part way upward towards top end 276 such that the remainderof file 274 is relatively smooth. More particularly, each file ispreferably configured with an abrading portion along less than abouthalf of the length of the file and more preferably about one-third ofthe length between tip 278 and top end 276. Accordingly, the abradingportion may have any suitable length such as 3 mm or 10 mm; however, theabrading portion in a preferred configuration is about 5 mm or about 6mm. The abrading portions as well as the tips can have a similar oridentical configuration to the abrading portions and tips of the filesdisclosed herein for cleaning either the operative middle portion of theroot canal or the apical root portion. However, the abrading portionsand tips are preferably rounded as shown in FIG. 21.

[0252] As indicated above, the length of a file such as files 274 a, 274b and 274 c is preferably sufficient such that when the file is insertedinto the root canal the tip can at least approximately reach the apexand the abrading portion 279 of the file can improve the access into theapical portion of the root canal. Although files used to improve theaccess into the apical root portion may be long enough to approximatelyreach the apex, the files can be used to improve the access as Ion asthe files can reach the bottom of the operative middle portion and thetop of the apical root portion. Such file lengths are typically within arange from about 8 mm to about 35 mm, more typically in a range fromabout 14 mm to about 35 mm and most typically in a range from about 12mm to about 33 mm. The length of the abrading portion is generallywithin a range from about 1 mm to about 35 mm, more preferably in arange from about 2 mm to about 16 mm and most preferably in a range fromabout 3 mm to about 6 mm. The abrading portion is preferably long enoughso that the entire apical portion can be abraded as well as at least thebottom of the operative middle portion. Note that stops such as stop 140may alternatively be utilized with instruments used to improve theaccess into the apical root portion.

[0253] In an optional set of instruments used to improve the access intoan apical root portion, the file tips of the instruments preferably allhave about the same diameter as shown in FIG. 21 at 278 a-d. Thediameter of the tips is generally within a range from about 0.06 mm toabout 1 mm, however, the tips preferably have a diameter of about 0.8mm. In a less preferred embodiment, the tip diameter of each file mayalso increase sequentially.

[0254] As shown in FIG. 21, the diameter of the abrading portions 279a-d increases from the tips 278 a-d towards the top of the abradingportions. The diameter of the abrading portion at the top is preferablywithin a range from about 0.1 mm to about 0.4 mm and is more preferablyin a range from about 0.2 mm to about 0.35 mm. As shown in FIG. 21, eachsuccessive file has an abrading portion, 279 a, 279 b, and 279 c whichis successively larger in diameter at the top of the abrading portionthan the abrading portion of the preceding file. Accordingly, a set mayhave files with abrading portions having the following respective topdiameters: about 0.2 mm, about 0.25 mm, about 0.3 mm and about 0.35 mm.Each abrading portion in such a set has a different taper as is shown inFIG. 21.

[0255]FIG. 21, however, also shows that the taper of the smooth or shankportions above the abrading portions may have essentially the same taperso that the taper of the shank portions remains essentially constant asthe different files in the set are sequentially inserted. However, theshanks portions may have any suitable configuration. Accordingly, thediameter at top end 273, in addition to being greater than the diameterof the abrading portion, can also be equal to or less than the diameterof abrading portion 279 or tip 278.

[0256] As mentioned above, the apical portion may be alternativelycleaned by abrading the apical portion. Typically, the instruments usedto optionally improve the access into the apical portion, the apicalportion access instruments, have the same lengths as the instrumentsoptionally used thereafter to abrade the apical portion so that theentire apical portion is first widened and then cleaned in an abrasivemanner. The instruments, however, have very different tip diameters andtapers along their respective abrading portions. The apical portionaccess instruments generally have much smaller tip diameters and muchgreater tapers than the instruments used to abrasively clean the apicalportion for safe widening of apical portions. Refer to Example 2 and theaccompanying FIGS. 36C-D for a discussion of specific instrumentsutilized and to observe the alteration of the apical portion after theapical portion widening phase and the apical portion cleaning phase.

[0257] The apical portion cleaning instruments are preferably formedfrom nickel/titanium as they are inserted further into the operativeroot canal than are the instruments used to clean the operative coronalportion and the operative middle portion. Since the apical portion istypically not as straight as the portions of the root canal above theapical portion, forming the files of the apical portion cleaninginstruments from nickel/titanium provides optimal flexibility. Note alsothat the apical portion cleaning instruments are typically manuallymoved so that these flexible files can be carefully maneuvered. Theinstruments used to optionally improve the access into the apicalportion may be formed from either stainless steel or nickel/titanium.

[0258] Before the apical root portion is abrasively cleaned, it ispreferable to obtain further x-ray images while an instrument isinserted into a root canal to determine the desired working length ofthe instrument. In establishing the working length, the state of theapex and the periapical tissues should also be considered. The statesmost frequently shown in radiography are shown in FIGS. 34A-C whereinthe apical portion of root canals 354 a-c of roots 352 a-c are depicted.FIG. 34A depicts a root canal 354 a of a vital tooth without periapicalrarefaction as shown by the normal border with the bone at 356 a. FIG.34B depicts an infected root canal 354 b without periapical rarefactionas shown by radiolucency 358 b. FIG. 34C depicts an infected root canal354 c with apical and periapical resorption as shown by radiolucency 358c. If the practitioner identifies the condition of the root canal asbeing that depicted in FIG. 34A or FIG. 34B, then the working length ofan instrument used to abrasively clean the apical root portion is in arange from about 0 to about 2 mm less than the distance from theocclusal surface to the radiographic apex of the tooth. However, if theroot canal condition is infected and has apical and periapicalresorption as depicted in FIG. 34C, then the apical root portion may beabrasively cleaned up to about 1.5 mm or about 0.5 mm from theradiographic apex or more particularly about 1 mm.

[0259] An example of an optional set of instruments designed forremoving and abrasively cleaning essentially all remaining pulp materialfrom the apical portion of a root canal is shown in FIG. 22. Theoptional set comprises three file instruments 280 a, 280 b and 280 c.Each file instrument comprises a handle 282 connected to a file 284.Each file 284 has a top end 283 where the file joins handle 282. Whenutilized to clean the apical root portion of a root canal, file 280 a isfirst introduced into the apical root portion followed by file 280 b andthen 280 c. Each file terminates at a tip 288 located opposite top end283.

[0260] An apical portion file instrument such as file instrument 280 aor a set of file instruments such as 280 a, 280 b, and 280 c arereferred to herein as apical portion cleaning instruments and areexamples of means for cleaning the apical root portion by abrading theapical root portion. More specifically, such instruments and sets ofinstruments as disclosed herein are examples of endodontic instrumentmeans for optionally, abrasively cleaning and removing essentially allremaining pulp material from the apical root portion after the pulpmaterial has been essentially removed from the operative middle portion.The file of each apical portion file instrument is an example ofoperative apical portion instrument means for movement within the apicalroot portion so as to effect removal and cleaning of pulp material asthe file instrument means is operatively moved. Note that the endodonticinstrument means for abrasively cleaning and removing essentially allremaining pulp material from the apical root portion after the pulpmaterial has been essentially removed from the operative middle portionand the means for cleaning the apical root portion by deliverying anirrigant into the apical portion after the pulp material has beenessentially removed from the operative middle portion are both examplesof means for cleaning the apical root portion after the pulp materialhas been essentially removed from the operative middle portion.

[0261] Tips 288 a-c can have any configuration, however, tips 288 a-cpreferably have minimal cutting capability to decrease the likelihood ofledging. An example of a suitable configuration for tips 288 a-c that isdesigned to minimize the cutting ability of the tips is that of theround tip shown in FIG. 17B.

[0262] Each file 284 of the file instruments designed for abrasivelycleaning the apical root portion of a root canal is configured to havean abrading portion 289 along at least a portion of the length of file284. The entire length of each file 284 can be configured with anabrading portion 289, however, abrading portion 289 preferably extendsfrom tip 288 part way upward towards top end 283 such that the remainderof file 284 is relatively smooth. More particularly, each file ispreferably configured with an abrading portion along less than abouthalf of the length of the file and more preferably about one-third ofthe length between tip 288 and top end 283. The abrading portion 289 canhave a similar or identical configuration to the abrading portion of thefile or files used to clean the operative middle portion of the rootcanal or the files used to improve the access into the apical rootportion.

[0263] The length of an optional apical portion abrading file such asfiles 284 a, 284 b and 284 c is sufficient such that when the files areinserted into the root canal the tips can at least approximately reachthe apex and the abrading portion 289 of the files can substantiallycontact and abrasively clean the pulp material in the apical portion ofthe root canal. Such file lengths are generally within a range fromabout 8 mm to about 35 mm, more typically in a range from about 14 mm toabout 35 mm and most typically in a range from about 12 mm to about 33mm. The length of the abrading portion is generally within a range fromabout 1 mm to about 35 mm, more preferably in a range from about 2 mm toabout 16 mm and most preferably in a range from about 3 mm to about 6mm. Note that stops such as stop 140 may alternatively be utilized withinstruments used to abrasively clean the apical root portion.

[0264] The diameter of the abrading portion is generally within a rangefrom about 0.06 mm to about 1.4 mm. As shown in FIG. 22, each successivefile has an abrading portion, identifed as 289 a-c, which issuccessively larger in diameter at the top of the abrading portion thanthe abrading portion of the preceding file.

[0265] The diameter of the tips 288 a-c of each optional apical portionabrading file may be increased incrementally such that each sequentiallyutilized abrasive cleaning instrument has a slightly larger tip diameterthan the preceding instrument as shown in FIG. 22 and FIG. 23 or thetips diameters may be about equal in diameter like the tips shown inFIG. 21.

[0266] Additionally, the taper of files 284 from tip 288 to the top endof the abrading portion may be constant as shown in FIG. 22. The tapermay also increase from file to file like the files shown in FIG. 21 orlike instruments shown in FIG. 35 in optional set 470. The diameter attop end 283 is shown being greater than the diameter of the abradingportion. However, the diameter at the top end of the file can also beequal to or less than the diameter of abrading portion 289 or tip 288.

[0267] The abrading portion 289 of each file 284 of file instruments 280is formed by twisting a blank so as to form a spiral. Files having suchspiral-type abrading portions are preferred. The abrading portion 289preferably has few spirals such that the action of abrading portion 289against the walls or surfaces of the apical portion of the root canal isrelatively gentle. Such an abrading portion is less aggressive as fewerspirals results in tines that have a wider angle.

[0268]FIG. 23 depicts an alternative embodiment of files configured foroptionally, abrasively cleaning the apical portion of a root canal. Theset of optional instruments depicted in FIG. 23 comprises three fileinstruments 290 a, 290 b and 290 c. Each file instrument comprises ahandle 292 connected to a file 294. Each file 294 has a shank portion296 above an abrading portion 298. Shank portion 296 a has substantiallythe same diameter along its length and the diameter of shank portion 296a is approximately the same as the diameter of shank portion 296 b and296 c. The diameter of abrading portion 298 a is essentially constantalong the length of abrading portion 298 a. Similarly, abrading portions298 b and 298 c also have substantially constant diameters. The diameterof abrading portion 298 b is larger than the diameter of abradingportion 298 a and the diameter of abrading portion 298 c is larger thanthe diameter of abrading portion 298 b.

[0269]FIG. 24 depicts an additional alternative embodiment of filesconfigured for optionally, abrasively cleaning the apical portion of aroot canal. The set of instruments depicted in FIG. 24 comprises threeoptional file instruments 300 a, 300 b and 300 c. Each file instrumentcomprise a handle 302 connected to a file 304. Each file 304 has a shankportion 306 above an abrading portion 308. Shank portion 306 a hassubstantially the same diameter along its length and the diameter ofshank portion 306 a is approximately the same as the diameter of shankportions 306 b and 306 c. Each abrading portion 308 extends from eachrespective shank portion 306 with a shape that is generally elliptical.Additionally, the width of each successive abrading portion 308 islarger than that of the preceding abrading portion. More specifically,the width of each successive abrading portion is larger at its midpointthan at the midpoint of the preceding abrading portion.

[0270]FIG. 25 depicts file 284 a inserted into apical portion 264 ofroot canal 252 a. The apical root portion file instruments are generallymoved in a different pattern compared to the operative middle portionfile instruments due primarily to the different perimeter anatomies ofthe two portions. A root canal generally becomes more cylindricaltowards the apical portion such that a root canal that has a perimeteranatomy that is essentially elliptical in shape within the operativemiddle portion tapers to an essentially cylindrically shaped perimeteranatomy within the apical portion.

[0271] An elliptical perimeter anatomy typically requires that thepractitioner move the file around the perimeter and/or flex the rotatingfile against the surfaces or walls in a milling motion such that the tipis moved to many locations around the perimeter. Due to the morecylindrical anatomy of an apical root portion, it becomes much lessnecessary, and virtually impossible to flex a rotating file in a millingmotion. It is generally adequate to merely rotate the file within theapical root portion and/or move the file in a longitudinal motion. Morespecifically, after the file reaches the apex or approximately reachesthe apex, the file is preferably moved upward while simultaneously beingrotated, and it is withdrawn in order to be cleaned before beingreintroduced.

[0272] Since file 284 a is generally not moved around the perimeter asin cleaning the operative middle portion, the center of motion, such asthe center of rotation, of file 284 a generally corresponds with thecenter of the root canal. In contrast, the center of motion when theoperative middle portion is cleaned is at various locations as the fileis moved around the root canal.

[0273] The files used to optionally clean the apical root portion in anabrasive manner can be designed for primarily longitudinal movement,rotational movement or combinations thereof. Since it is generally notnecessary to flex a file when abrasively cleaning the apical rootportion as the apical root portion is typically rounder than othersections of a root canal, apical root portion files need not necessarilyhave the same properties as the operative middle portion files in termsof flexibility, rigidity and resilience. The files used to abrasivelyclean the apical portion are, however, preferably sufficiently flexibleto adjust to the anatomy or structure of a root canal in a manner thatenables the tip of the file to reach the apex. The files also preferablyhave sufficient rigidity to apply pressure against the walls or surfacesof the root canal as the abrading portion of the file is urged againstthe walls of the root canal and simultaneously moved in an abrasivecleaning motion even after the file has moved throughout the length ofthe root canal. Additionally, an optional file configured for abrasiveuse in an apical root portion preferably has adequate resilience toavoid being substantially deformed as the file passes through a rootcanal and also as the abrading portion is applied against the walls ofthe root canal.

[0274]FIG. 26A depicts a longitudinal cross-sectional view of tooth 240after both root canals 252 a and 252 b have been cleaned. FIG. 26Bdepicts a cross-sectional view of tooth 240 taken along cutting line26B-26B in FIG. 26A. From the view shown in FIG. 26B, it is clear thatessentially all pulp material 250 has been removed from root canal 252a.

[0275]FIG. 26C is a transverse cross-sectional view of root canal 252 ataken along cutting line 26C-26C in FIG. 26A through cementum 248 anddentin 244 to depict the configuration of the cleaned and shaped rootcanal. The view shown in FIG. 26C shows in phantom lines the originalconfiguration of the perimeter of the pulp canal 252 a and theconfiguration of the cleaned and shaped walls 268 a.

[0276] While the root canal is cleaned, it is also generallysimultaneously shaped for subsequent filling with a filling materialsuch as gutta percha. Cleaning and shaping a root canal, such as pulpcanal 252 a, to yield a cleaned and shaped root canal, such as shapedwalls 268 a, generally necessitates the widening of portions of the pulpcanal and smoothing some contours of the pulp canal to yield a wider andsmoother canal. The amount of dentin removed during the cleaning andshaping is preferably no more than just sufficient to adequately shapethe root canal for subsequent filling.

[0277] Because the perimeter of the root canal is followed duringcleaning and shaping of the root canal, particularly the coronal portionand the operative middle portion, the original anatomy of the root canalor shape of the perimeter is substantially maintained. Accordingly, whenthe original perimeter is, for example, generally elliptical such as thecross-sectional shape of pulp canal 252 a, the resulting cleaned andshaped root canal has a perimeter that is still generally ellipticalsuch as shaped walls 268 a as shown in FIG. 26C. Similarly, if theoriginal shape of the perimeter of a root canal as seen from atransverse cross-sectional view, such as the anatomies or perimeterconfigurations shown in FIGS. 7, 8 and 9B, is generally circular,laminar or tear shaped, then the cleaned and shaped walls will also begenerally circular or tear shaped. In other words, the original anatomyof the root-canal controls the shape of the resulting cleaned and shapedanatomy due to the cleaning techniques enabled by the present invention.

[0278] In contrast, prior art methods yield a final anatomy that isdictated by the shape of the instrument. As shown in FIGS. 15A-F, priorart methods result in an anatomy with a significant footprint from theinstrument without even cleaning all of the perimeter of the root canal.In addition to failing to fully clean the root canal, the tooth can beoverly thinned, perforations may result or the tooth may beunnecessarily weakened when cleaned by such prior art methods.

[0279] FIGS. 27A-27J are transverse cross-sections of exemplary filesthat can be utilized to clean the operative middle portion, tooptionally improve the access to the apical root portion or tooptionally clean the apical root portion of the root canal in anabrasive manner. Each file has a different abrading portion. All of thefiles in combination with their respective abrading portions disclosedherein are examples of means for abrasively removing and cleaning ofpulp material as the file instrument is operatively moved. Additionally,each abrading portion disclosed herein is an example of a means forabrading a root canal.

[0280] Conventional file designs can also be utilized within the scopeof the present invention. Accordingly, the files are not limited to thedesigns shown in FIGS. 27A-27J. The files preferably, however, areconfigured in a manner such that when the potential for breakage isminimized. For example, a file with a square cross-section may bepreferred over a triangular cross-section as the file with a squarecross-section has a greater mass and is accordingly less likely tobreak. Additionally, a file configured with tines or extensions havingwide angles are generally preferred over those with narrow angles.However, the preferred tine configuration depends primarily on theparticular use as in some instances it is desirable to aggressively cutwhile in others the root canal can be passively cut. When it is moredesirable to aggressively cut, it may be preferred for example toutilize a file with relatively narrow tines.

[0281]FIG. 27J depicts a file 310 with a generally square-shapedtransverse cross-section and truncated corners 312. Abrasive grit orabrasive material 314 is located on truncated corners 312. Similarlysuch abrasive grit can be located around a file having anycross-sectional shape and be an effective abrading portion. The abrasivegrit may be any of the abrasive materials discussed above such asdiamonds.

[0282] The transverse cross-section of a file shown at FIG. 27Acorresponds to a file as shown in FIG. 17A. In FIG. 28, a fileinstrument 320 is shown cleaning operative middle portion 160 of a rootcanal. Instrument 320 has a handle 322 connected to file 324 formed bymachining a groove into a metal blank. Note that handle 322 is adaptedfor manual use, however, a handle such as handle 202 designed formechanical rotation may also be used.

[0283]FIG. 29 depicts another embodiment of a file instrument shown at330. File instrument 330 has a handle 332 which is particularly adaptedfor use with a mechanical instrument. The file instruments of thepresent invention can, however, be utilized with any suitable handleconfiguration. All of the handles disclosed herein are examples of endmeans for grasping and operatively moving a file in an abrasive action.

[0284] File instrument 330 further comprises a file 334 which ispreferably used to clean the operative middle portion. File 334 has anabrading portion comprising protrusions or barbs 335 at the upper end ofthe file and a combination of barbs 335 and knurled surface 337 at thelower end. FIGS. 30-33 are depictions of various tips of files withinthe scope of the present invention.

EXAMPLES OF THE PREFERRED EMBODIMENTS

[0285] Testing was conducted to identify some of the anatomicalcharacteristics of different teeth. The results of this testing arereported in Example 1. Additionally, Example 2-4 are hypotheticalexamples presented solely to illustrate some embodiments of the presentinvention. Note that reference is made in Example 2 to FIG. 35 and FIGS.36A-D. The hypothetical examples are not to be construed as limiting thespirit and scope of the invention as these hypothetical examples wereproduced in furtherance of reducing the present invention to practice.

EXAMPLE 1

[0286] Table 2 and Table 3 presented hereinbelow provide data regardingthe anatomical characteristics of root canals of different teeth. Moreparticularly, average measurements are provided of the canal diametersand the wall thicknesses of root canals at a location 2 mm from the apexof each root canal. A practioner should bear these average measurementsin mind when optionally widening the apical portion or cleaning theapical portion. Note that the roots of the first molars are referencedby their position with the abreviations m, v, d, and l for the termsmesial, vestibular, distal and lingual. TABLE 2 Root Canal AnatomicalCharacteristics Average Avergae Average Average Average Average Numberof Distance Mesio-Distal Vestibulo- Vestibular Lingual Mesial DistalMaxillary Roots From the Canal Distal Canal Wall Wall Wall Wall TeethExamined Apex Diameter Diameter Thickness Thickness Thickness ThicknessCentral 20 2 mm 0.39 mm 0.38 mm 0.93 mm 1.12 mm 0.91 mm 1.05 mm IncisorsLateral 20 2 mm 0.23 mm 0.39 mm 0.87 mm 1.09 mm 0.81 mm 0.77 mm IncisorsFirst 20 2 mm 0.25 mm 0.20 mm 0.88 mm 0.65 mm 0.95 mm 0.80 mm PremolarsSecond 20 2 mm 0.27 mm 0.23 mm 1.16 mm 0.99 mm 0.99 mm 0.86 mm PremolarsFirst Molar 25 2 mm 0.18 mm 0.32 mm 1.04 mm 1.07 mm 0.73 mm 0.82 mm m-vRoot First Molar 25 2 mm 0.21 mm 0.23 mm 0.87 mm 0.81 mm 0.89 mm 0.85 mmd-v Root First Molar 25 2 mm 0.23 mm 0.22 mm 0.68 mm 0.85 mm 0.85 mm1.03 mm 1 Root

[0287] TABLE 3 Root Canal Anatomical Characteristics Number AverageAverage Average Average Average Average of Distance Mesio-DistalVestibulo- Vestibular Lingual Mesial Distal Mandibular Roots From theCanal Distal Canal Wall Wall Wall Wall Teeth Examined Apex DiameterDiameter Thickness Thickness Thickness Thickness Central 30 2 mm 0.22 mm0.40 mm 1.06 mm 1.12 mm 0.72 mm 0.72 mm Incisors Lateral 25 2 mm 0.22 mm0.28 mm 0.76 mm 0.71 mm 0.73 mm 0.67 mm Incosirs Canines 30 2 mm 0.29 mm0.36 mm 0.95 mm 0.10 mm 0.71 mm 0.77 mm First Molars 30 2 mm 0.39 mm0.38 mm 1.21 mm 1.25 mm 0.94 mm 0.94 mm m Root First Molar 30 2 mm 0.23mm 0.54 mm 1.23 mm 1.28 mm 0.87 mm 0.92 mm d Root

EXAMPLE 2

[0288] This example describes, in relation to FIG. 35 and FIGS. 36A-36D,an exemplary system and method for cleaning a root canal after the rootcanal has been properly accessed. After a tooth has been identified asrequiring root canal therapy, an x-ray image is obtained in order todetermine the state of health of a tooth as well as the structure andanatomical characteristics of the tooth. After all carious tissue hasbeen removed and any old fillings have been infiltrated, a dam isinstalled.

[0289] Before the instruments designed for use in the operative middleportion or the apical portion of the root canal are utilized, the pulpchamber must be properly opened so that adequate access can be gained tothe anatomical root canal. Access is gained by removing the top of thepulp chamber, preferably with an appropriate diamond bur instrument. Thecontents in the pulp chamber are then removed with the aid ofappropriate irrigants. Examples of appropriate irrigants includehydrogen peroxide, primarily for use in the canals of living teeth, orsodium hypochlorite, primarily for the canals in necrotic teeth. Ifdesired a cuspidectomy may be performed.

[0290] It is then preferable to remove or reduce dentinal or enamelprotrusions or irregularities such as dentinal shelves, that may obscureor hinder access of instruments into the operative root canal byrectification of such protrusions with an appropriate instrument whichpreferably utilizes diamonds for abrasion. FIG. 36A depicts a tooth 740before the removal of dentinal shelf 266 above root canal 252 a. Dottedline 550 in FIG. 36A depicts the desired realignment throughrectification in order to provide greater access for instrumentationduring the subsequent phases. Rectified root canal 252 a depicted inFIGS. 36B-D after subsequent phases shows that rectification wouldenable an instrument to be inserted in a relatively straight mannerthough the operative coronal portion 260 and the operative middleportion 262. Although, an instrument would need to flex within theapical portion 264 of root canal 252 a due to its curvature, therequired flexing is minimized as a result of the removal of dentinalshelf 266 above root canal 252 a. Since the apical portion of root canal252 b is essentially straight, rectification of dentinal shelf 266 aboveroot canal 252 b would also enable an instrument to be inserted up toapex 254 b through the apical portion 264 in an essentially straightconfiguration.

[0291] The progressive phases depicted in FIGS. 36A-D are similar to thephases shown in FIGS. 19A, 19F, 25 and 26. For example, FIG. 36A depictsthe same phase as is shown in FIG. 19A. FIGS. 36A-D, however, betterdepict the changes of the shape of pulp canal 252 a after each phase.The same numbers are used for the elements of tooth 740 as are used fortooth 240. Note that pulp material 250 is not shown in FIGS. 36A-D sothat the changes to pulp canal 252 a are clearly visible after eachphase. As discussed hereinbelow, FIGS. 36B-D respectively depict rootcanal 252 a of tooth 740 after cleaning operative coronal portion 262,after widening apical portion 264 and after cleaning apical portion 264.

[0292] After any necessary rectification, the working length isdetermined for the files used to clean the operative middle portion. Theappropriate working length is determined by radiographically identifyingthe length of the operative root canal and then subtracting 3 mm fromthe length identified from the x-ray image. It is necessary to subtract3 mm from the overall x-ray length in order to compensate for anydistortions in the x-ray image and to avoid interfering with the apicalportion while the operative middle portion is being prepared. Afteridentifying the length of the root canal of a tooth and determining theworking length of the files to be used, instruments can then be selectedwhich have a length such that essentially all pulp material can beanatomically cleaned from the operative middle portion of a root canalwithout significantly removing pulp material from the apical rootportion.

[0293]FIG. 35 depicts three sets of instruments identified at 410, 440and 470 which are used to prepare a root canal. The sets of instrumentsidentified respectively at 410, 440 and 470 are respectively used toclean the operative middle portion, to improve access into the apicalportion and to clean the apical root portion.

Operative Middle Portion Phase and Related Sets of Instruments

[0294] Tables 4A, 4B and 4C presented hereinbelow describe thedimensions of three different set of instruments which can be used toclean the operative middle portion in different teeth depending on theparticular operative root canal length. These three sets are preferablysold as part of a kit. Although, the kit includes several sets ofinstruments, only one set of instruments is typically used for cleaningthe operative middle portion. The practitioner selects from several setsin the kit depending on the particular length of the operative coronalportion and the operative middle portion. The instruments in Tables 4A,4B and 4C have lengths which are respectively 16 mm, 17 mm and 20 mm.

[0295] In this example, the set of operative middle portion instrumentsselected for use in a tooth is the set presented in Table 4C due to thecombined length of the operative coronal portion and the operativemiddle portion of the operative root canal. The set of instruments forcleaning the operative middle portion detailed in Table 4C correspondswith the set of instruments shown in FIG. 35 at 410. Since only one setof instruments is used to clean the operative middle portion only oneset is shown in FIG. 35 at 410. TABLE 4A Operative Middle PortionInstruments (16 mm) Total Abrading Shank Diameter at Shank LengthPortion Portion Tip the top of the Portion Abrading Instrument of theFile Length Length Diameter Abrading Diameter Portion Number (L₂ + L₃)(L₁) (L₃) (D₁) Portion (D₃) (D₄) Taper 1 16 mm 14 mm 2 mm .10 mm .38 mm.50 mm .02 2 16 mm 14 mm 2 mm .13 mm .69 mm .70 mm .04

[0296] TABLE 4B Operative Middle Portion Instruments (17 mm) TotalAbrading Shank Diameter at Shank Length of Portion Portion Tip the topof the Portion Abrading Instrument the File Length Length DiameterAbrading Diameter Portion Number (L₂ + L₃) (L₁) (L₃) (D₁) Portion (D₃)(D₄) Taper 1 17 mm 15 mm 2 mm .10 mm .40 mm .50 mm .02 2 17 mm 15 mm 2mm .10 mm .70 mm .70 mm .04

[0297] TABLE 4C Operative Middle Portion Instruments (20 mm) TotalAbrading Shank Diameter of Shank Length of Portion Portion Tip the topof the Portion Abrading Instrument the File Length Length DiameterAbrading Diameter Portion Number (L₂ + L₃) (L₁) (L₃) (D₁) Portion (D₃)(D₄) Taper 1 20 mm 18 mm 2 mm .10 mm .46 mm .50 mm .02 2 20 mm 18 mm 2mm .13 mm .85 mm .90 mm .04

[0298] As shown in Tables 4A, 4B and 4C, the operative middle portioninstruments in the sets may have exactly the same tip diameters or mayhave tip diameters which are essentially the same. More particularly,the instruments in the set detailed in Table 4B both have a tip diameterof 0.10 mm while the instruments in the sets presented in Table 4A andTable 4C have a tip diameter of either 0.10 mm or 0.13 mm. In each set,the second instrument has a greater taper than the file of the firstinstrument.

[0299] As indicated above, set 410 corresponds with the set presented inTable 4C. As shown, instruments 410 a and 410 b have files 414 a and 414b. Each file has a shank portion 416 which tapers to an abrading portion419 configured like conventional K-files and terminating at a tip 418.Smooth shank portion 416 may be used to accommodate stops to adjust theworking length of file 414. Note that the file of each instrumentdetailed in Tables 4A, 4B and 4C has a 2 mm smooth portion or shankportion above the abrading portion. Handles 412 a and 412 b arerespectively positioned on smooth shank portions 416 a and 416 b. Thesehandles are configured for attachment to a handpiece. The sets ofinstruments presented in Table 4A and 4B have a similar appearance toset 410, however, the files of the instruments in Table 4B have anabrading portion configured to correspond with Hedstrom-type files.

[0300] The operative middle portion instruments in each set are formedfrom stainless steel. The instruments all have sufficient rigidity toapply pressure against root canal surfaces as each instrument is flexedor curved against root canal surfaces and simultaneously moved in acleaning motion. Each instrument also has adequate resilience to avoidbeing substantially deformed as the instrument is flexed or curved tourge the abrading portion against root canal surfaces and as theinstrument is simultaneously moved in a cleaning motion. Accordingly, apractitioner can move the instrument around the perimeter of theoperative middle portion of the root canal using the contours of theoperative middle portion as a guide for the movement of the instrumentsuch that the original anatomy is enlarged and not significantlyaltered.

[0301] After set 410, as detailed in Table 4C, is selected, the pulpchamber is flooded with an irrigation fluid or filled with a chelatinglubricant gel, if the canal is atresic. The instruments in set 410 arethen attached to a handpiece to move the instruments in either arotating or reciprocating motion. These instruments can also be manuallymoved. Instrument 410 a and then 410 b are then sequentially urgedagainst the root canal for about one minute in conformance with theanatomy of the root canal. More particularly, the instruments areapplied to the perimeter of the canal, acting on any protuberances orjagged edges in order to rectify the first two portions, the operativemiddle portion and the operative coronal portion, while still conformingto the anatomy of the canal.

[0302] After cleaning the operative middle portion, the root canal mayappear as does root canal 252 a of tooth 740 shown in FIG. 36B. FIG. 36Bshows that dentinal shelf 266 has been fully rectified. The othercontours of root canal 252 a have been followed to clean operativemiddle portion 262. As a result, the diameter of the root canal inoperative middle portion 262 has been widened, although, the originalperimetrical anatomy has not been substantially altered, particuarly inthe bottom half of the operative middle portion 262 of root canal 252 a.

[0303] A third instrument may also be added to each set of instrumentswhich is an aggresive abrasion instrument having the same dimensions asthe second instrument in each set. Each aggresive abrasion instrumentmay have an abrading portion equally divided between an upper sectioncovered with abrasive particles such as diamonds and a lower sectionthat is twisted like the abrading portions of the other instruments inthe sets. So for example, a third instrument in set 410 having a filewith an upper section configured for aggresive abrasion has an abradingportion that is 18 mm long below a shank portion that is 2 mm long. Theupper half of the shank portion is not twisted and is covered withdiamonds while the lower half is twisted and has a length of about 9 mm.

[0304] If the instruments are configured with a handle that enables themto be used with a handpiece configured for adjusting the working lengthof the instrument, such as is disclosed in U.S. patent application Ser.No. 09/425,849 and Ser. No. 09/425,857 referenced above, then thelengths of the file, the abrading portion and the shank portion arelonger. More particularly, instead of lengths of 16 mm, 14 mm and 2 mmfor the total file length, abrading portion length and shank portionlength of the instruments described in Table 4A, the respective lengthsare 19 mm, 16 mm and 3 mm. Similarly, the lengths of the instrumentslisted in Table 4B as being 17 mm, 15 mm, 2 mm for the total filelength, abrading portion length and shank portion length of theinstruments are respectively 23 mm, 20 mm and 3 mm when attached to ahandle that enables the instrument to be used in a manner such that itcan be moved within the chuck of the handpiece. Finally, the lengths ofthe instruments listed in Table 4C as being 20 mm, 18 mm, 2 mm for thetotal file length, abrading portion length and shank portion length ofthe instruments are respectively 27 mm, 24 mm and 3 mm when attached toa handle that enables the instrument to be used in a manner such that itcan be moved within the chuck of the handpiece.

Apical Portion Widening Phase and Related Sets of Instruments

[0305] A probe is then inserted to the apex of the root canal andanother x-ray image is obtained. After the length has been determinedthe accessibility of the apical portion is assessed. If the apicalportion is initially to small to permit entry of an irrigation cannulathen an optional set of instruments is selected for use in improving theaccess into the apical root portion or stated otherwise to enlarge theconstricted region between the operative middle portion and the apicalportion. This is achieved by manually moving one or more instrumentsuntil the transition zone between the operative middle portion and theapical root portion has been appropriately instrumented to have adiameter of about 0.40 mm, which is suitable for accommodating thediameters of the smallest irrigation needles.

[0306] Again the practitioner has a comprehensive kit with several setsof instruments which are designed for improving access into the apicalroot portion after the pulp material has been removed from the operativemiddle portion of a root canal. Each set is designed for use in a toothwith a different operative root canal length. Accordingly, only one setfrom the kit is selected for use in operative root canal based on thelength of the particular anatomical root canal being treated.

[0307] Tables 5A, 5B and 5C detail the dimensions of instruments withfile lengths which are respectively 21 mm, 25 mm and 30 mm. In thisexample, the set presented in Table 5B is selected. The set presented inTable 5B is shown in FIG. 35 as set 440. TABLE 5A Apical WideningInstruments (21 mm) Total Length Abrad. Square Round Abrad Square Shankof File Portion Portion Portion Tip Portion Portion Portion Inst. (L₁ +L₃ + Length Length Length Diam Diam. Diam. Diam. No. L₄) (L₁) (L₄) (L₃)(D₁) (D₂) (D₃) (D₄) Taper 1 21 mm 5 mm 11 mm 5 mm .08 mm .28 mm .30 mm.80 mm .04 2 21 mm 5 mm 11 mm 5 mm .08 mm .38 mm .40 mm 1.1 mm .06

[0308] TABLE 5B Apical Widening Instruments (25 mm) Total Length Abrad.Square Round Tip Abrad Square Shank of File Portion Portion PortionDiame- Portion Portion Portion Inst. (L₁ + L₃ + Length Length Length terDiam. Diam. Diam. No. L₄) (L₁) (L₄) (L₃) (D₁) (D₂) (D₃) (D₄) Taper 1 25mm 5 mm 15 mm 5 mm .08 mm .28 mm .30 mm .90 mm .04 2 25 mm 5 mm 15 mm 5mm .08 mm .38 mm .40 mm 1.3 mm .06

[0309] TABLE 5C Apical Widening Instruments (30 mm) Total Length Abrad.Square Round Tip Abrad Square Shank of File Portion Portion PortionDiame- Portion Portion Portion Inst. (L₁ + L₃ + Length Length Length terDiam. Diam. Diam. No. L₄) (L₁) (L₄) (L₃) (D₁) (D₂) (D₃) (D₄) Taper 1 30mm 5 mm 20 mm 5 mm .08 mm .28 mm .30 mm 1.1 mm .04 2 30 mm 5 mm 20 mm 5mm .08 mm .38 mm .40 mm 1.6 mm .06

[0310] The files of the instruments in the sets detailed in Tables 5A,5B and 5C are formed from stainless steel or nickel/titanium. Each filehas three sections including a smooth shank portion, a square portionand an abrading portion. As indicated above, the set presented in Table5B corresponds with set 440 shown in FIG. 35. Note, however, with theexception of length, the instruments detailed in Table 5A and Table 5Cwould appear just like set 440. Instrument 440 a has a file 444 a withsmooth shank portion 446 a, a square portion 447 a, an abrading portion449 a and a file tip 448 a. As shown, the smooth shank portion 446 a isthe top section of file 444 a and a handle 442 is positioned on shankportion 446 a. Smooth shank portion 446 a tapers to square portion 447 awhich is between shank portion 446 a and abrading portion 449 a.

[0311] The smooth shank portion enables stops be positioned on the fileto adjust the working length of the file. Each smooth shank portion ofeach file has a length of about 5 mm with various diameters. Theinstruments can be used for all operative lengths that are likely to beencountered in clinical practice through the positioning of the stops atthe predetermined lengths. While the instruments can be offered in amore expanded series of millimetrically different lengths, the use ofstops is acceptable, particularly since, these instruments are manuallymoved.

[0312] In each set, the diameter at the top of the square portion ofinstrument number 1 and instrument number 2 is respectively 0.30 mm and0.40 mm. The abrading portion is formed by twisting the square sectionso that the abrading portion has a K-file configuration. The instrumentsin each set all have the same tip diameters. The taper of the files fromthe tip (D₁) to the diameter at the top of the square portion (D₃)remains constant and is respectively 0.04 and 0.06 for instrument number1 and instrument number 2 in each set.

[0313] Preferably, instrument 1 is first utilized and then instrument 2to obtain, in a gradual manner, the desired enlargement of the specifictransition zone between the operative middle portion and the apicalportion. This enlargement is also preferably achieved withoutsignificantly changing the diameter of the apical portion of the canal.Accordingly, the tip diameter (D₁) of the various instruments in thisset remains constant while the diameter at the top of the cutting areaor abrading portion (D₂), located 5 mm from the tip, is graduated fromone instrument to the next, reaching a maximum diameter of 0.38 mm. Therest of the shaft, up to the handle, does not have a cutting surface. Tothe extent that these instruments are used to expand the apical portionof the canal, the practitioner should constantly bear in mind theaverage diameters of the canals and the average thicknesses of theparietal walls at the apex, as listed in Table 2 and Table 3.

[0314] After widening the apical portion of the root canal with the setshown at 440 in FIG. 35 and as detailed in Table 5B, the root canal mayappear as does root canal 252 a in FIG. 36C with a widened apicalportion 264. More particuarly, the region of root canal 252 a extendingfrom the bottom of operative middle portion 262 to the top half ofapical portion 264 has been noticeably widened. The bottom half ofapical portion 264 has also been widened but to a much lesser degree.

Apical Portion Cleaning Phase and Related Sets of Instruments

[0315] After the access into the apical portion has been adequatelywidened as discussed hereinabove and as shown in FIG. 36C, the apicalportion is cleaned. Cleaning is halted at the working length asdetermined by the operator which should be at the apex. The practitionershould determine this length beforehand, based on the biologicalcondition of the apico-periapical region, in terms of the morphometricsof the diameters and thicknesses at the apex as set forth in the Table 2and Table 3, and in accordance with the amount of widening to be appliedto the apical portion of the canal.

[0316] In this example, Example 2, a set of instruments is decribed forcleaning the apical portion in an abrasive manner after the portion ofthe root canal above the apical portion has been cleaned. In Example 4,the preferred method of cleaning of the apical portion throughirrigation is used in combination with the instruments described abovein this example for cleaning the portions above the apical portion.

[0317] Again sets of instruments are provided with each set having adifferent length. Three sets of instruments are described hereinbelowwhich are designed for removing and cleaning essentially all pulpmaterial from the apical root portion after access into the apical rootportion has been improved by a set of instruments such as set 440detailed in Table 5B. In some instances, the instruments described inthis example can also be used to clean the pulp material from the rootcanal immediately after the operative middle portion has been cleaned bya set of instruments such as the sets presented in Table 4C.

[0318] Tables 6A, 6B and 6C detail the dimensions of instruments withfile lengths which are respectively 21 mm, 25 mm and 30 mm. However,please note that only instruments from Table 6B are used in the toothbeing cleaned in this example. The set of instruments detailed in Table6B are shown in FIG. 35 as set 470. Set 470 includes instruments 470 a-lwhich respectively correspond with instruments 1-12 in the set presentedin Table 6B.

[0319] The instruments in set 470 have a similar appearance as theinstruments in set 440. Instruments 470 a-l have a handle 472 opposite afile 474. Each file is formed from nickel/titanium. Each file 474 has asmooth shank portion 476 a, a square portion 477, an abrading portion479 and a file tip 478. The sets of instruments presented in Table 6Aand 6C have a similar appearance to instruments detailed in Table 6B andshown at 470, however, the files have different lengths. The taper ofthe files from the tip (D₁) to the diameter at the top of the squareportion (D₃) is provided in each table. TABLE 6A Apical CleaningInstruments (25 mm) Total Length Abrad. Spuare Round Tip Abrad SpuareShank of File Portion Portion Portion Diam- Portion Portion PortionInst. (L₁ + L₃ + Length Length Length eter Diam. Diam. Diam. No. L₄)(L₁) (L₄) (L₃) (D₁) (D₂) (D₃) (D₄) Taper  1 21 mm 5 mm 11 mm 5 mm .10 mm.20 mm .42 mm .50 mm 0.02  2 21 mm 5 mm 11 mm .15 mm .25 mm .47 mm .50mm 0.02  3 21 mm 5 mm 11 mm 5 mm .20 mm .30 mm .52 mm .60 mm 0.02  4 21mm 5 mm 11 mm 5 mm .25 mm .375 mm .65 mm .70 mm 0.025  5 21 mm 5 mm 11mm 5 mm .30 mm .425 mm .70 mm .70 mm 0.025  6 21 mm 5 mm 11 mm 5 mm .35mm .475 mm .75 mm .80 mm 0.025  7 21 mm 5 mm 11 mm 5 mm .40 mm .525 mm.80 mm .80 mm 0.025  8 21 mm 5 mm 11 mm 5 mm .50 mm .625 mm .90 mm .90mm 0.025  9 21 mm 5 mm 11 mm 5 mm .60 mm .725 mm 1.0 mm 1.0 mm 0.025 1021 mm 5 mm 11 mm 5 mm .70 mm .825 mm 1.1 mm 1.1 mm 0.025 11 21 mm 5 mm11 mm 5 mm .80 mm .925 mm 1.2 mm 1.2 mm 0.025 12 21 mm 5 mm 11 mm 5 mm1.0 mm 1.125 mm 1.4 mm 1.5 mm 0.025

[0320] TABLE 6B Apical Cleaning Instruments (25 mm) Total Length Abrad.Spuare Round Tip Abrad Spuare Shank of File Portion Portion PortionDiam- Portion Portion Portion Inst. (L₁ + L₃ + Length Length Length eterDiam. Diam. Diam. No. L₄) (L₁) (L₄) (L₃) (D₁) (D₂) (D₃) (D₄) Taper  1 25mm 5 mm 15 mm 5 mm .10 mm .20 mm .50 mm .50 mm 0.02  2 25 mm 5 mm 15 mm5 mm .15 mm .25 mm .55 mm .60 mm 0.02  3 25 mm 5 mm 15 mm 5 mm .20 mm.30 mm .60 mm .60 mm 0.02  4 25 mm 5 mm 15 mm 5 mm .25 mm .375 mm .75 mm.80 mm 0.025  5 25 mm 5 mm 15 mm 5 mm .30 mm .425 mm .80 mm .80 mm 0.025 6 25 mm 5 mm 15 mm 5 mm .35 mm .475 mm .85 mm .90 mm 0.025  7 25 mm 5mm 15 mm 5 mm .40 mm .525 mm .90 mm .90 mm 0.025  8 25 mm 5 mm 15 mm 5mm .50 mm .625 mm 1.0 mm 1.0 mm 0.025  9 25 mm 5 mm 15 mm 5 mm .60 mm.725 mm 1.1 mm 1.1 mm 0.025 10 25 mm 5 mm 15 mm 5 mm .70 mm .825 mm 1.2mm 1.2 mm 0.025 11 25 mm 5 mm 15 mm 5 mm .80 mm .925 mm 1.3 mm 1.3 mm0.025 12 25 mm 5 mm 15 mm 5 mm 1.0 mm 1.125 mm 1.5 mm 1.5 mm 0.025

[0321] TABLE 6C Apical Cleaning Instruments (30 mm) Total Length Abrad.Spuare Round Tip Abrad Square Shank of File Portion Portion PortionDiam- Portion Portion Portion Inst. (L₁ + L₃ + Length Length Length eterDiam. Diam. Diam. No. L₄) (L₁) (L₄) (L₃) (D₁) (D₂) (D₃) (D₄) Taper  1 30mm 5 mm 20 mm 5 mm .10 mm .20 mm .60 mm .60 mm 0.02  2 30 mm 5 mm 20 mm5 mm .15 mm .25 mm .65 mm .70 mm 0.02  3 30 mm 5 mm 20 mm 5 mm .20 mm.30 mm .70 mm .70 mm 0.02  4 30 mm 5 mm 20 mm 5 mm .25 mm .375 mm .875mm .90 mm 0.025  5 30 mm 5 mm 20 mm 5 mm .30 mm .425 mm .925 mm 1.0 mm0.025  6 30 mm 5 mm 20 mm 5 mm .35 mm .475 mm .975 mm 1.0 mm 0.025  7 30mm 5 mm 20 mm 5 mm .40 mm .525 mm 1.025 mm 1.1 mm 0.025  8 30 mm 5 mm 20mm 5 mm .50 mm .625 mm 1.125 mm 1.2 mm 0.025  9 30 mm 5 mm 20 mm 5 mm.60 mm .725 mm 1.225 mm 1.3 mm 0.025 10 30 mm 5 mm 20 mm 5 mm .70 mm.825 mm 1.325 mm 1.4 mm 0.025 11 30 mm 5 mm 20 mm 5 mm .80 mm .925 mm1.425 mm 1.5 mm 0.025 12 30 mm 5 mm 20 mm 5 mm 1.0 mm 1.125 mm 1.625 mm1.7 mm 0.025

[0322] After the apical portion has been properly widened, thepractitioner selects a set of files having the appropriate length, suchas one of the sets presented in Tables 6A, 6B or 6C. To ensure that thefiles have an appropriate working length, it may be necessary to placestops around the shank portions of the files identified for example at416 a, 446 a and 476 a. The practitioner then selects an instrument fromthe set identifed as having an appropriate length for introduction intothe root canal down to the apical portion.

[0323] As indicated above, in this example, an instrument is selectedfrom the set detailed in Table 6B, which is shown in FIG. 35 as set 470.After selecting an instrument, the practitioner then determines, basedon feel and experience, whether the file is appropriately sized orwhether a larger or smaller file is needed. For instance, if thepractitioner selects instrument number 2 from the set detailed in Table6B and shown in FIG. 35 at 470 b which has a tip diameter of 0.15 mm andthe file binds after insertion, then the practitioner would switch toinstrument number 1 which has a tip diameter of 0.10 mm. Similarly, ifinstrument number 2 is too loose then the practitioner would then switchto instrument number 3 which has a tip diameter of 0.20 mm. Thepractitioner then uses that appropriately sized instrument to clean theapical portion of the root canal by hand. If the practitioner concludesafter using an appropriately sized file, that further instrumentation isstill needed within the apical portion then the instrument with the nextlargest file may be used. It is typically unnecessary to use a thirdinstrument with an even larger file after using a series of twoinstruments However, the practitioner may clean the apical root portionwith a series of more than two instruments as deemed necessary by thepractitioner in order to fully clean the apical portion.

[0324] After the apical portion of the root canal has been cleaned withthe set shown at 470 in FIG. 35 and as detailed in Table 6B, the rootcanal may appear as does root canal 252 a shown in FIG. 36D with acleaned apical portion 264. More particuarly, after use of an instrumentsuch as instrument 2 from Table 6B shown at 470 b, apical portion 264may appear as shown. Note that cleaning apical portion 264 hassubstantially widened the bottom half of apical portion 264 while thetop half is less significantly flared when compared to its appearancebefore being cleaned. The appearance of apical portion 264 results fromthe different configurations of the respective abrading portions ofinstruments used to widen and to clean the apical portion. Moreparticularly, the diameter of the tip (D₁) and the diameter at the topof the abrading portion (D₂) of the last instrument used to widen theapical portion, instrument 440 b, are respectively 0.8 mm and 0.38 mmwhile instrument 470 b has a tip diameter (D₁) of 0.15 mm and thediameter at the top of the abrading portion (D₂) is 0.25 mm Statedotherwise, the 0.06 taper of abrading portion 449 b results in muchgreater flaring than the 0.02 taper of abrading portion 479 b while thelarge tip diameter of instrument 440 b causes the widening of the lowerhalf of apical portion 264.

[0325] Set 410 and set 440 are preferably disposed after use. However,since only one or two instruments from set 470 are used, it ispreferable to replace or clean the instruments used from set 470. All ofthe sets of instruments described in this example may be sold togetheras a comprehensive kit or various sets may be grouped together as kitsintended for use with teeth of particular lengths. For example, the setsused in the tooth cleaned in this example which are detailed in Table4C, 5B and 6B may be sold together. Additionally, since set 410 and set440 are intended to be single use sets these sets may also be soldtogether as a single use disposable kit.

EXAMPLE 3

[0326] This example describes another exemplary system for cleaning aroot canal after the root canal has been properly accessed.

Operative Middle Portion Instruments

[0327] The sets of instruments designed for use in the operative middleportion of a root canal are set in Tables 7A, 7B and 7C. In contrast tothe sets of operative middle portion instruments described in Example 2,each of these sets include four instruments instead of only twoinstruments. The lengths of the files in these sets include the variouslengths that are likely to be encountered in clinical practice whichrange predominantely but not exclusively from 15 mm to 20 mm. Longerlengths, 25 mm, are typically needed for the middle segment of canineteeth. Accordingly, the files in each set of instruments have thefollowing respective lengths: 17 mm, 20 mm and 25 mm. The lengths of theinstruments in these three sets encompass the average variations inlength that are likely to be encountered in clinical practice and interms of the overall length of the operative coronal portion and theoperative middle portion of various operative canals. However, pleasenote that other sets may also be useful as these three sets are merelyillustrative. For example, it may be useful to have a greater series ofsets with lengths ranging from 15 mm to 20 mm in 1 mm increments and anadditional set having a length of 25 mm.

[0328] As in Example 2, one set of instruments is selected based on thelength of the tooth. Accordingly, after the length of the operativemiddle portion has been determined then either the set of instrumentsdetailed in Table 7A, 7B or 7C is selected and if necessary stops may beutilized to adjust the working length of the file. When the length ofthe operative middle portion has been appropriately determined, each ofthese sets of instruments can be used to anatomically clean essentiallyall pulp material from the operative middle portion of a root canalwithout significantly removing pulp material from the apical rootportion. TABLE 7A Operative Middle Portion Instruments (17 mm) Diameterat top Instrument Total Length Abrading Tip Diameter of the AbradingNumber of the File Portion (D₁) Portion (D₂) 1 17 mm 17 mm .10 mm .40 mm2 17 mm 17 mm .13 mm .50 mm 3 17 mm 17 mm .13 mm .70 mm 4 17 mm 17 mm.13 mm .90 mm

[0329] TABLE 7B Operative Middle Portion Instruments (21 mm) Diameter attop Instrument Total Length Abrading Tip Diameter of the Abrading Numberof the File Portion (D₁) Portion (D₂) 1 20 mm 20 mm .10 mm .45 mm 2 20mm 20 mm .13 mm .55 mm 3 20 mm 20 mm .13 mm .75 mm 4 20 mm 20 mm .13 mm.95 mm

[0330] TABLE 7C Operative Middle Portion Instruments (25 mm) Diameter attop Instrument Total Length Abrading Tip Diameter of the Abrading Numberof the File Portion (D₁) Portion (D₂) 1 25 mm 25 mm .10 mm .55 mm 2 25mm 25 mm .10 mm .65 mm 3 25 mm 25 mm .13 mm .75 mm 4 25 mm 25 mm .13 mm.95 mm

[0331] The instruments in the sets detailed in Table 7A and Table 7Binclude a first instrument with a tip diameter of about 0.10 mm whilethe other instruments have a tip diameter of about 0.13 mm. The firstand second instruments in the set presented in Table 7C have tipdiameters of about 0.10 mm while the third and fourth instruments havetip diameters of about 0.13 mm. It is often useful to begininstrumenting with a slightly smaller tip diameter, however, thedifference in diameter is so small that these tip diameters areconsidered to be essentially the same size. The difference isparticularly insignificant when compared with the incremental increasein the size of the diameter tip from instrument to instrument ofconventional instruments used in conventional cleaning techniques.

[0332] The sets of instruments described in this example would beexpected to require more time to use than the instruments described inExample 2 as there are more instruments in each set. However, all of thesets can be used to clean the operative middle portion withoutsubstantially changing the original anatomy of the root canal. Moreparticularly, each instrument is configured to enable a practitioner tomove the file along a side of the operative middle portion in a mannersuch that the original anatomy is enlarged without being modified tohave just the shape of the instrument.

[0333] Note that the abrading portion of each file extends along theentire length of each file. Accordingly, each file is capable ofsimultaneously abrading both the operative coronal portion and theoperative middle portion. In any event, the abrading portion extendsbeyond the conventional 16 mm length of instruments in present use.

[0334] Since sets are provided in different lengths it is not necessaryto use stops to adjust the length of the file as the handle of theinstrument ensures that the instrument stops safely at the properworking depth. Thus, the use of sets of instruments with graduatedlengths eliminates the problems associated with traditional stoppingdepths. More particularly, the sets reduce the amount of time requiredto position the instruments at the desired length and eliminate the riskof bacterial contamination of the instruments due to handling.

Apical Portion Widening Instruments

[0335] The access into the apical portion is improved, if necessary,after the operative middle portion has been cleaned. More particularly,it is necessary to widen the access into the apical root portion of theroot canal in order to enable irrigants to be delivered as needed. Thedimensions of a set of instruments which can be used for this purposeare set forth in Table 5. The files of each instrument have a length ofabout 35 mm and an abrading portion which is about 5 mm long. TABLE 8Apical Widening Instruments (35 mm) Total Length Abrading Diameter ofthe Portion Tip the top of Instrument File (L₁ + Length Diameter theAbrading Number L₃ + L₄) (L₁) (D₁) Portion (D₂) Taper 1 35 mm 5 mm .08mm .20 mm .020 2 35 mm 5 mm .08 mm .25 mm .020 3 35 mm 5 mm .08 mm .30mm .036 4 35 mm 5 m  .08 mm .35 mm .045

[0336] The instruments would each be expected to be useful for improvingaccess into the apical root portion after the pulp material has beenremoved from the operative middle portion of a root canal. However, sucha set of instruments would be expected to require more time to use thanone of the sets of instruments described in Example 2 as there are moreinstruments in this set.

Apical Portion Cleaning Instruments

[0337] After the access into the apical portion has been adequatelywidened, the apical portion is cleaned. One of the sets of instrumentsdetailed in Tables 6A, 6B or 6C may be used to clean the apical portionor alternatively the set detailed in Table 9 may be used. Eachinstrument in the set described in Table 9 has a file with a workinglength of about 35 mm and an abrading portion which is about 5 mm long.The files of the instruments all have the same tip diameters and haveincreasing larger tapers. TABLE 9 Total Length Abrading Diameter at ofthe Portion Tip the top of Instrument File (L₁ + Length Diameter theAbrading Number L₃ + L₄) (L₁) (D₁) Portion (D₂) Taper 1 35 mm 5 mm .06mm .18 mm .02 2 35 mm 5 mm .08 mm .20 mm .02 3 35 mm 5 mm .10 mm .22 mm.02 4 35 mm 5 mm .15 mm .27 mm .02 5 35 mm 5 mm .20 mm .32 mm .02 6 35mm 5 mm .25 mm .37 mm .02 7 35 mm 5 mm .30 mm .42 mm .02 8 35 mm 5 mm.35 mm .47 mm .02 9 35 mm 5 mm .40 mm .52 mm .02

[0338] The set of instruments detailed in Table 9 have longer files thanthe sets provided in Tables 6A, 6B and 6C so more stops would benecessary. In most other respects the set in Table 9 is very similar tothe other sets discussed in Example 2 for cleaning the apical portion.Note, however, that the set in Table 9 begins with smaller tip diameterswhich may be useful in some instances.

EXAMPLE 4

[0339] This example describes an exemplary system for cleaning a rootcanal without abrasively cleaning the apical portion. The apical portionis cleaned after the operative middle portion has been cleaned with set410 as set forth in Example 2. Access into the apical portion may alsohave been improved through the use of set 440 as described in Example 2.Cleaning of the apical portion is then initiated by inserting a cleaninginstrument into the apical portion as shown in FIG. 20A and FIG. 20B anddeliverying irrigants. The cleaning instrument is a cannula 760 of anendodontic irrigator tip 720, as previously described in reference toFIG. 20A and FIG. 20B. After syringe 790 has been used to deliverirrigants into root canal 782, the irrigants and any remaining debrismay be removed by any suitable method such as aspiration using irrigatortip 720 coupled to an aspirator device so that the tooth appears asshown in FIG. 20B at 780.

[0340] Note in addition to set 410 and set 440 being disposable afteruse, irrigator tip 720 is also preferably disposable. Note also thatinstead of a large set of instruments like set 470, only a singleirrigator tip need be used so it is much less expensive to merelyirrigate. It is also less time intensive since it is not necessary touse a series of apical instruments. All of the instruments described inthis example may be sold individually or together as a comprehensivekit.

[0341] The present invention may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrated and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. A method for cleaning the operative coronal portion, theoperative middle portion and the apical root portion of the operativeroot canal of a tooth, the method comprising: exposing the root canal byremoving a portion of the tooth at a crown thereof and by removing thetop of the pulp chamber; obtaining at least one endodontic instrumenthaving a stainless steel file with an abrading portion for removing pulpmaterial, the file having a length corresponding to at least thecombined length of the operative coronal portion and the operativemiddle portion; inserting the file of the endodontic instrument into theoperative coronal portion and the operative middle portion; removing andcleaning essentially all pulp material from the operative coronalportion and the operative middle portion by flexing the file to urge theabrading portion of the instrument against root canal surfaces withinthe operative middle portion as the instrument is rotated and moved in acleaning motion in conformance with the anatomical shape of theoperative middle portion by following the contours of the operativemiddle portion as a guide for movement of the instrument, and withoutsignificantly extending the file of the instrument into the apical rootportion; obtaining at least one apical portion cleaning instrumenthaving a nickel/titanium file with an abrading portion for removing pulpmaterial; and cleaning the apical root portion after the pulp materialhas been essentially removed from the operative coronal portion and theoperative middle portion by abrading the apical root portion with thenickel/titanium file of the apical portion cleaning instrument.
 2. Amethod as defined in claim 1 , wherein following the contours of theoperative middle portion involves moving the instrument around theperimeter of the operative middle portion of the operative root canal.3. A method as defined in claim 1 , wherein following the contours ofthe operative middle portion involves moving the instrument along a sideof the operative middle portion such that the instrument generally hasmore than one center of motion during the step of removing and cleaningessentially all pulp material from the operative coronal portion and theoperative middle portion of the operative root canal.
 4. A method asdefined in claim 1 , wherein the file has an end means for grasping andoperatively moving the file in an abrasive action.
 5. A method asdefined in claim 1 , further comprising the step of determining theworking length of the operative root canal to select an appropriateinstrument for removing and cleaning essentially all pulp material fromthe operative coronal portion.
 6. A method as defined in claim 1 ,further comprising the step of positioning a stop of the file of theendodontic instrument.
 7. A method as defined in claim 1 , furthercomprising the step of minimizing obstructions in the operative rootcanal before removing and cleaning essentially all pulp material fromthe operative middle portion such such that instruments can be insertedin the operative middle portion in a relatively straight manner.
 8. Amethod as defined in claim 1 , further comprising the step of improvingaccess into the apical root portion after the pulp material has beenessentially removed from the operative middle portion.
 9. A method foranatomical cleaning of the operative coronal portion, the operativemiddle portion and the apical root portion of an operative root canal ina tooth, the method comprising: exposing the root canal by removing aportion of the tooth at a crown thereof and by removing the top of thepulp chamber; obtaining a set of first endodontic instruments whereineach instrument has a stainless steel file with an abrading portion forremoving pulp material, each file having a length corresponding to atleast the combined length of the operative coronal portion and theoperative middle portion; removing and cleaning essentially all pulpmaterial from the operative coronal portion and the operative middleportion by sequentially introducing the files of the instruments in theset of first endodontic instruments into the operative middle portionand then flexing each file such that the abrading portion of each fileis urged against root canal surfaces within the operative middle portionas each instrument is rotated and moved in a cleaning motion inconformance with the anatomical shape of the operative middle portion byfollowing the contours of the operative middle portion as a guide formovement of each instrument, and without significantly extending thefile of each instrument into the apical root portion; obtaining at leastone apical portion cleaning instrument having a nickel/titanium filewith an abrading portion for removing pulp material; and cleaning theapical root portion after the pulp material has been essentially removedfrom the operative coronal portion and the operative middle portion byabrading the apical root portion with the nickel/titanium file of theapical portion cleaning instrument.
 10. A method as defined in claim 9 ,wherein following the contours of the operative middle portion involvesmoving each instrument around the perimeter of the operative middleportion of the operative root canal.
 11. A method as defined in claim 9, wherein following the contours of the operative middle portioninvolves moving each instrument along a side of the operative middleportion of the operative root canal such that each instrument generallyhas more than one center of motion during the step of removing andcleaning essentially all pulp material from the operative middleportion.
 12. A method as defined in claim 9 , wherein each file of eachinstrument in the set of first endodontic instruments comprises has atip opposite a top end, and wherein the files of all of the instrumentsin the set of first endodontic instruments have essentially the same tipdiameter while having distinct top end diameters to enable the files tobe sequentially introduced into the operative middle portion such thateach successive file has a greater top end diameter than that of thepreceding file.
 13. A method as defined in claim 9 , wherein each fileof each instrument in the set of first endodontic instruments has a tipopposite a top end, and wherein the files of all of the instruments inthe set of first endodontic instruments have distinct tapers to enablethe files to be sequentially introduced into the operative middleportion such that each successive file has a greater taper than that ofthe preceding file.
 14. A method as defined in claim 9 , wherein thefile of each instrument in the set of first endodontic instrumentsextends from a handle.
 15. A method as defined in claim 9 , furthercomprising the step of determining the working length of the operativeroot canal to select an appropriate instrument for removing and cleaningessentially all pulp material from the operative coronal portion and theoperative middle portion.
 16. A method as defined in claim 9 , furthercomprising the step of positioning at least one stop on the file of eachinstrument in the set of first endodontic instruments sequentiallyintroduced into the operative middle portion.
 17. A method as defined inclaim 9 , further comprising the step of minimizing obstructions in theoperative root canal before removing and cleaning essentially all pulpmaterial from the operative middle portion such such that instrumentscan be inserted in the operative middle portion in a relatively straightmanner.
 18. A method as defined in claim 9 , further comprising the stepof improving access into the apical root portion after the pulp materialhas been essentially removed from the operative middle portion.
 19. Amethod for anatomical cleaning of the operative coronal portion, theoperative middle portion and the apical root portion of an operativeroot canal in a tooth, the method comprising: exposing the root canal byremoving a portion of the tooth at a crown thereof and by removing thetop of the pulp chamber; obtaining a set of first endodontic instrumentswherein each instrument has a stainless steel file with a top end thatextends from an end means for grasping and operatively moving the file,wherein the file has a tip opposite from the top end, wherein the filehas an abrading portion for removing pulp material, and wherein eachfile has a length corresponding to at least the combined length of theoperative coronal portion and the operative middle portion; removing andcleaning essentially all pulp material from the operative coronalportion and the operative middle portion by sequentially introducing thefiles of the instruments in the set of first endodontic instruments intothe operative middle portion such that each successive file has agreater top end diameter than that of the preceding file, and thenflexing each file such that the abrading portion of each file is urgedagainst root canal surfaces within the operative middle portion as eachinstrument is rotated and moved in a cleaning motion in conformance withthe anatomical shape of the operative middle portion by following thecontours of the operative middle portion as a guide for movement of eachinstrument, and without significantly extending the file of eachinstrument into the apical root portion; obtaining at least one apicalportion cleaning instrument having a nickel/titanium file with anabrading portion for removing pulp material; and cleaning the apicalroot portion after the pulp material has been essentially removed fromthe operative coronal portion and the operative middle portion byabrading the apical root portion with the nickel/titanium file of theapical portion cleaning instrument.
 20. A method as defined in claim 19, wherein following the contours of the operative middle portioninvolves moving each instrument around the perimeter of the operativemiddle portion of the operative root canal.
 21. A method as defined inclaim 19 , wherein following the contours of the operative middleportion involves moving each instrument along a side of the operativemiddle portion of the operative root canal such that each instrumentgenerally has more than one center of motion during the step of removingand cleaning essentially all pulp material from the operative middleportion.
 22. A method as defined in claim 19 , wherein the files of allof the instruments in the set of first endodontic instruments haveessentially the same tip diameter.
 23. A method as defined in claim 19 ,wherein the end means for grasping and operatively moving the file is ahandle.
 24. A method as defined in claim 9 , further comprising the stepof determining the working length of the operative root canal to selectan appropriate instrument for removing and cleaning essentially all pulpmaterial from the operative coronal portion and the operative middleportion.
 25. A method as defined in claim 9 , further comprising thestep of positioning at least one stop on the file of each instrument inthe set of first endodontic instruments sequentially introduced into theoperative middle portion.
 26. A method as defined in claim 19 , furthercomprising the step of minimizing obstructions in the operative rootcanal before removing and cleaning essentially all pulp material fromthe operative middle portion such such that instruments can be insertedin the operative middle portion in a relatively straight manner.
 27. Amethod as defined in claim 19 , further comprising the step of improvingaccess into the apical root portion after the pulp material has beenessentially removed from the operative middle portion.
 28. An endodonticinstrument system adapted for anatomical cleaning of the operativecoronal portion, the operative middle portion and the apical rootportion of an operative root canal in a tooth, the endodontic instrumentsystem comprising: a first endodontic instrument means for anatomicallyremoving and anatomically cleaning essentially all pulp material fromthe operative middle portion, said first endodontic instrument meansincluding operative middle portion instrument means for flexiblyconforming to the anatomical shape of the operative middle portion so asto effect removal and cleaning of pulp material as the first instrumentmeans is operatively moved, said operative middle portion instrumentmeans being formed from stainless steel, said operative middle portioninstrument means having means for abrading root canal surfaces, saidoperative middle portion instrument means having a length correspondingto at least the combined length of the operative coronal portion and theoperative middle portion in order to remove pulp material fromessentially all of the operative middle portion of the operative rootcanal, said operative middle portion instrument means being able to flexsuch that the abrading means is urged against root canal surfaces whilethe first endodontic instrument means is rotated and moved in a cleaningmotion, thereby enabling contours of the operative middle portion to beused as a guide for movement of the operative middle portion instrumentmeans in conformance to the anatomical shape of the operative middleportion, and end means for grasping and operatively moving in anabrasive action the operative middle portion instrument means whilebending and flexing the operative middle portion instrument means; and asecond endodontic instrument means for abrasively cleaning and removingessentially all remaining pulp material from the apical root portionafter the pulp material has been essentially removed from the operativecoronal portion and the operative middle portion, said second endodonticinstrument means including operative apical portion instrument means formovement within the apical root portion so as to effect removal andcleaning of pulp material as the second instrument means is operativelymoved, the operative apical portion instrument means being formed fromnickel/titanium, and end means for grasping and operatively moving in anabrasive action the operative apical portion instrument means.
 29. Anendodontic instrument system as defined in claim 28 , wherein theoperative middle portion instrument means has sufficient rigidity toapply pressure against the root canal surfaces via the abrading means asthe operative middle portion instrument means is flexed to urge theabrading means against root canal surfaces and simultaneously moved in acleaning motion.
 30. An endodontic instrument system as defined in claim28 , wherein the operative middle portion instrument means is configuredto enable a practitioner to move the operative middle portion instrumentmeans around the perimeter of the operative middle portion of theoperative root canal.
 31. An endodontic instrument system as defined inclaim 28 , wherein the operative middle portion instrument means is afile having a tip and wherein the file is configured to enable apractitioner to move the file along a side of the operative middleportion in a manner such that the tip does not remain primarily in oneposition as the operative middle portion is cleaned.
 32. An endodonticinstrument system as defined in claim 28 , wherein the first endodonticinstrument instrument means comprises a set of instruments, wherein eachoperative middle portion instrument comprises a file having a tipopposite a top end, wherein the files of all of the instruments in theset have essentially the same tip diameter while having distinct top enddiameters to enable the files to be sequentially introduced into theoperative middle portion such that each successive file has a greatertop end diameter than that of the preceding file.
 33. An endodonticinstrument system as defined in claim 28 , wherein the first endodonticinstrument instrument means comprises a set of instruments, wherein eachoperative middle portion instrument comprises a file, wherein the filesof all of the instruments in the set have distinct tapers to enable thefiles to be sequentially introduced into the operative middle portionsuch that each successive file has a greater taper than that of thepreceding file.
 34. An endodontic instrument system as defined in claim28 , further comprising a stop configured to be positioned on theoperative middle portion instrument means in order to limit insertion ofthe file into the operative coronal portion and the operative middleportion without substantially extending into the apical portion.
 35. Anendodontic instrument system as defined in claim 28 , further comprisingan endodontic instrument means for improving access into the apical rootportion after the pulp material has been essentially removed from theoperative middle portion by the first endodontic instrument means suchthat irrigants can be delivered into the apical portion of the operativeroot canal from an irrigation needle.
 36. An endodontic instrumentsystem adapted for anatomical cleaning of the operative coronal portion,the operative middle portion and the apical root portion of an operativeroot canal in a tooth, the endodontic instrument system comprising: afirst endodontic instrument configured for use in the operative middleportion of an operative root canal to anatomically clean essentially allpulp material from the operative middle portion, the first endodonticinstrument including a file having a top end opposite a tip, said filehaving a length corresponding to at least the combined length of theoperative coronal portion and the operative middle portion in order toremove pulp material from essentially all of the operative middleportion of the operative root canal, the file having an abrading portionfor removing pulp material, the file being able to flex such that theabrading portion is urged against root canal surfaces while the file isrotated and moved in a cleaning motion, thereby enabling contours of theoperative middle portion to be used as a guide for movement of the filein conformance to the anatomical shape of the operative middle portionwhile effecting removal and cleaning of pulp material from essentiallyall of the operative middle portion, and a handle connected to the topend of the file, the handle being configured to enable a user tooperatively move the file in an abrasive action while bending andflexing the file within the operative middle portion of the operativeroot canal; and an apical portion cleaning instrument adapted forcleaning the apical root portion after the pulp material has beenessentially removed from the operative coronal portion and the operativemiddle portion, the apical portion cleaning instrument including ahandle and a file extending from the handle, the file being formed fromnickel/titanium.
 37. An endodontic instrument system as defined in claim36 , wherein the file of the first endodontic instrument has sufficientrigidity to apply pressure against the root canal surfaces via theabrading portion as the file is flexed to urge the abrading portionagainst root canal surfaces and as the file is simultaneously moved in acleaning motion.
 38. An endodontic instrument system as defined in claim36 , wherein the file of the first endodontic instrument is configuredto enable a practitioner to move the file around the perimeter of theoperative middle portion of the operative root canal.
 39. An endodonticinstrument system as defined in claim 36 , wherein the file of the firstendodontic instrument is configured to enable a practitioner to move thefile along a side of the operative middle portion in a manner such thatthe tip does not remain primarily in one position as the operativemiddle portion is cleaned.
 40. An endodontic instrument system asdefined in claim 36 , wherein the file of the apical portion cleaninginstrument has a top end opposite a tip, the file having a length thatenables the file to reach within the apical portion of the operativeroot canal, the file having an abrading portion for removing pulpmaterial, the abrading portion being located on a portion of the filesuch the abrading portion can be moved against the root canal to cleanthe apical portion of the operative root canal.
 41. An endodonticinstrument system as defined in claim 36 , further comprising anotherendodontic instrument configured for improving access into the apicalroot portion after the pulp material has been essentially removed fromthe operative middle portion by the first endodontic instrument suchthat irrigants can be delivered into the apical portion of the operativeroot canal from an irrigation needle.
 42. An endodontic instrumentsystem as defined in claim 36 , further comprising a stop configured tobe positioned on the file of the first endodontic instrument in order tolimit insertion of the file into the operative coronal portion and theoperative middle portion without substantially extending into the apicalportion.
 43. An endodontic instrument system adapted for anatomicalcleaning of the operative coronal portion, the operative middle portionand the apical root portion of an operative root canal in a tooth, theendodontic instrument system comprising: a set of first endodonticinstruments configured for sequential use in the operative middleportion of an operative root canal to anatomically clean essentially allpulp material from the operative middle portion, each instrument in theset including a file having a tip opposite a top end, the file beingformed from stainless steel, the file having a length corresponding toat least the combined length of the operative coronal portion and theoperative middle portion in order to remove pulp material fromessentially all of the operative middle portion of the operative rootcanal, the file having an abrading portion for removing pulp material,the abrading portion being located on the file and extending from thetip along at least most of the file toward the top end, the file beingable to flex such that the abrading portion is urged against root canalsurfaces while the file is rotated and moved in a cleaning motion,thereby enabling contours of the operative middle portion to be used asa guide for movement of the file in conformance to the anatomical shapeof the operative middle portion while effecting removal and cleaning ofpulp material from essentially all of the operative middle portion, anda handle connected to the top end of the file, the handle beingconfigured to enable a user to operatively move the file in an abrasiveaction while bending and flexing the file within the operative middleportion of the operative root canal; and a set of apical portioncleaning instruments adapted for cleaning the apical root portion afterthe pulp material has been essentially removed from the operativecoronal portion and the operative middle portion, each apical portioncleaning instrument including a handle and a file formed fromnickel/titanium.
 44. An endodontic instrument system as defined in claim43 , wherein the file of each instrument in the set of first endodonticinstruments has sufficient rigidity to apply pressure against the rootcanal surfaces via the abrading portion as each file is flexed to urgethe abrading portion against root canal surfaces and as each file issimultaneously moved in a cleaning motion.
 45. An endodontic instrumentsystem as defined in claim 43 , wherein the file of each instrument inthe set of first endodontic instruments has adequate resilience to avoidbeing substantially deformed as each file is flexed to urge the abradingportion against root canal surfaces and as each file is simultaneouslymoved in a cleaning motion.
 46. An endodontic instrument system asdefined in claim 43 , wherein the file of each instrument in the set offirst endodontic instruments is configured to enable a practitioner tomove the file around the perimeter of the operative middle portion ofthe operative root canal.
 47. An endodontic instrument system as definedin claim 43 , wherein the file of each instrument in the set of firstendodontic instruments is configured to enable a practitioner to movethe file along a side of the operative middle portion in a manner suchthat the tip does not remain primarily in one position as the operativemiddle portion is cleaned.
 48. An endodontic instrument system asdefined in claim 43 , wherein the file of each instrument in the set offirst endodontic instruments has essentially the same length.
 49. Anendodontic instrument system as defined in claim 43 , wherein the filesof all of the instruments in the set of first endodontic instrumentshave essentially the same tip diameter while having distinct top enddiameters to enable the files to be sequentially introduced into theoperative middle portion such that each successive file has a greatertop end diameter than that of the preceding file.
 50. An endodonticinstrument system as defined in claim 43 , wherein the files of all ofthe instruments in the set of first endodontic instruments have distincttapers to enable the files to be sequentially introduced into theoperative middle portion such that each successive file has a greatertaper than that of the preceding file.
 51. An endodontic instrumentsystem as defined in claim 43 , wherein the file of each apical portioncleaning instrument has a top end opposite a tip, each file having alength that enables it to reach within the apical portion of theoperative root canal, each file having an abrading portion located on aportion of the file such the abrading portion can be moved against theroot canal to clean the apical portion of the operative root canal. 52.An endodontic instrument system as defined in claim 43 , furthercomprising another endodontic instrument configured for improving accessinto the apical root portion after the pulp material has beenessentially removed from the operative middle portion by the instrumentsin the set of first endodontic instruments such that irrigants can bedelivered into the apical portion of the operative root canal from anirrigation needle.
 53. An endodontic instrument system as defined inclaim 36 , further comprising a stop configured to be positioned on oneof the files of the first endodontic instruments in order to limitinsertion of the file into the operative coronal portion and theoperative middle portion without substantially extending into the apicalportion.
 54. An endodontic instrument system adapted for anatomicalcleaning of the operative coronal portion, the operative middle portionand the apical root portion of an operative root canal in a tooth, theendodontic instrument system comprising: a set of first endodonticinstruments configured for sequential use in the operative middleportion of an operative root canal to anatomically clean essentially allpulp material from the operative middle portion without significantlyextending into the apical root portion, each instrument in the setincluding a file having a tip opposite a top end, the file being formedfrom stainless steel, the file having a length corresponding to at leastthe combined length of the operative coronal portion and the operativemiddle portion in order to remove pulp material from essentially all ofthe operative middle portion of the operative root canal, the filehaving an abrading portion for removing pulp material, the abradingportion being located on the file and extending from the tip along atleast most of the file toward the top end, the file being able to flexsuch that the abrading portion is urged against root canal surfaceswhile the file is rotated and moved in a cleaning motion, therebyenabling contours of the operative middle portion to be used as a guidefor movement of the file in conformance to the anatomical shape of theoperative middle portion while effecting removal and cleaning of pulpmaterial from essentially all of the operative middle portion, whereinthe files of all of the instruments in the set of first endodonticinstruments have essentially the same length and tip diameter whilehaving distinct top end diameters to enable files to be sequentiallyintroduced into the operative middle portion such that each successivefile has a greater top end diameter than that of the preceding file; anda handle connected to the top end of the file such that movement of thehandle also moves at least the top end of the file along a common axiswith the handle, the handle being configured to enable a user tooperatively move the file in an abrasive action while flexing the filewithin the operative middle portion of the operative root canal; and aset of apical portion cleaning instruments adapted for cleaning theapical root portion after the pulp material has been essentially removedfrom the operative coronal portion and the operative middle portion,each apical portion cleaning instrument including a handle and a fileformed from nickel/titanium.